PROBLEMS/SYMPTOMS:
"There was a problem uninstalling the game and now I can't reinstall."
Or, "RTW does not work now, but it was working in the past!"
Or, "I want to totally remove all RTW and just start over again!"
Or, "When I try to install RTW, it only tries to 'uninstall'"
Or, "I've uninstalled RTW, but RTW still appears in Control Panel, Add/Remove Programs!"

IMPORTANT: This is not tested with BI (I have not bought BI yet), though it should fix most BI install/reinstall problems.

INTRO:
This is the procedure I use in fixing RTW computers. It has been used a lot (I just tested & revised it again with bad installs of Patch 1.5), but read and understand it before plowing in. It will solve about 80% of the most common install/reinstall problems, and is based on official Activision procedures. If registry entries/program files are missing/nonexistant when at a step to remove them, just continue anyway. Do not arbitrarily skip steps unless you understand why you are doing so. The penalty, however, is just that you could have wasted your time and need to do the whole thing again if your next install attempt fails. This procedure will allow RTW to reinstall in many cases.

ASSUMPTIONS:
1. No overclocking
2. System has a known stable power supply
3. Motherboard BIOS and Video Card BIOS is up to date, and properly configured
4. System is clean & relatively free of dust inside (e.g., no heating/fan problems)
5. No viruses (strongly recommend NOD32 over all other AV programs!)
6. No spyware or adware (suggest freeware Spybot - Search & Destroy)
7. No rootkits: since early 2005, that your have never had any Sony music CD in your computer (specifically, that the undetectable Sony rootkit has ever been installed you your machine... even if it has been supposedly 'removed')
8. Disable Anti-virus protection & close all background programs and unnecessary processes (use CTRL-ALT-DEL and also look in the Tray)
9. Assuming game was installed to default C:\, with Windows XP SP2 system default directory names
10: Before beginning, back up any RTW files you want to keep, like savegames, preferences.txt, etc.
11. Normal RTW uninstall (e.g., via Control Panel) tried, but failed.
12. You are not using cracks, hacks, nocd, warez files, cloak/hide software, etc.
13. You use an original RTW disk #1 to run the game.

WARNING:
This procedure is for an Advanced user. Some parts are based/quoted on official Acitvision solutions. Read/understand the whole procedure before beginning. Do not attempt registry changes if you are not comfortable editing the Registry (however, you will not be able to do the manual uninstall without Regedit). It is a good idea to back up your registry FIRST, and also KNOW HOW TO RESTORE IT! Know this: Altering the *wrong* things in the registry could result in complete operating system failure. Get someone to help you if you are not sure!

DETAILED PROCEDURE:
You can manually remove RTW from your system in 4 steps:
STEP 1. Remove the registry entries
STEP 2. Remove the game files
STEP 3. Remove the RomeTW.ini
STEP 4. Remove the Installer files

Note 01: If any of the following keys are already removed (e.g., you carefully look, and they are simply not there, then go to the next step. Remember which ones are gone and post about it.
Note 02: It may help viewing to turn off WORD WRAP in notepad (or your editor).
Note 03: The Objective of STEP 1 is to delete certain registry keys.
Note 04: In Regedit, you can enable View - StatusBar and look at the bottom of the Regedit window to see the full name of the key you are looking at -- Take a look at it to carefully VERIFY you are deleting the correct key.
Note 05: The Appendix lists the keys which will be removed.

---- STEP 1. Remove the registry entries ----

1-01) Click Start then Run.
1-02) At the prompt type: REGEDIT. The registry editor will open.
1-03) Click the "+" next to HKEY_CURRENT_USER.
1-04) Click the "+" next to SOFTWARE.
1-05) Right-Click & delete the "The Creative Assembly" entry (the sub-keys will be deleted too).

Selecting a key to delete: note that the highlighted key appears in the Status Bar with it FULL key name... be sure to double-check this!

Right-click on a key to get the fly-out menu; choose Delete to delete it. Again, double-ckeck the full key name in the Status Bar.
ALL the sub-keys and sub-data will be deleted, too!

1-06) Click the "+" next to HKEY_LOCAL_MACHINE.
1-07) Click the "+" next to SOFTWARE.
1-08) Right-Click & delete the "The Creative Assembly" entry (the sub-keys will be deleted too).
1-09) Go back to HKEY_LOCAL_MACHINE\SOFTWARE.
1-10) Click the "+" next to Microsoft
1-11) Click the "+" next to Windows
1-12) Click the "+" next to CurrentVersion
1-13) Click the "+" next to Uninstall
1-14) Delete the key(s) named: {4089999C-6CB7-4F9D-A2F6-DB158DBF91FB}
                               {B6BB246A-D1AC-2414-D84D-13C8F3D38C43}
                               {A642BB6B-CA1D-4142-8DD4-318C3F3DC834}
                               {A5D65411-8E73-4C85-AD80-9FE8B7391CF9}
1-15) Delete the key(s) named: InstallShield_{4089999C-6CB7-4F9D-A2F6-DB158DBF91FB}
                               InstallShield_{B6BB246A-D1AC-2414-D84D-13C8F3D38C43}
                               InstallShield_{A642BB6B-CA1D-4142-8DD4-318C3F3DC834}
                               InstallShield_{A5D65411-8E73-4C85-AD80-9FE8B7391CF9}
1-16) Click the "+" next to InstallShield Uninstall Information
1-17) Delete the key(s) named: {4089999C-6CB7-4F9D-A2F6-DB158DBF91FB}
                               {B6BB246A-D1AC-2414-D84D-13C8F3D38C43}
                               {A642BB6B-CA1D-4142-8DD4-318C3F3DC834}
                               {A5D65411-8E73-4C85-AD80-9FE8B7391CF9}
1-18) Go back to HKEY_LOCAL_MACHINE\SOFTWARE.
1-19) Click the "+" next to Classes
1-20) Click the "+" next to Installer
1-21) Click the "+" next to Features
1-22) Delete the key(s) named: 4089999C-6CB7-4F9D-A2F6-DB158DBF91FB
                               B6BB246A-D1AC-2414-D84D-13C8F3D38C43
                               A642BB6B-CA1D-4142-8DD4-318C3F3DC834
                               A5D65411-8E73-4C85-AD80-9FE8B7391CF9
1-23) Go back one level to Installer: Click the "+" next to Installer
1-24) Click the "+" next to Products
1-25) Delete the key(s) named: 4089999C-6CB7-4F9D-A2F6-DB158DBF91FB
                               B6BB246A-D1AC-2414-D84D-13C8F3D38C43
                               A642BB6B-CA1D-4142-8DD4-318C3F3DC834
                               A5D65411-8E73-4C85-AD80-9FE8B7391CF9
1-26) Go back to HKEY_LOCAL_MACHINE\SOFTWARE.
1-27) Click the "+" next to SEGA
1-28) Delete the key named "Rome Total War - patch 1.3"

Click & highlight "My Computer", then choose Edit - Find (or CTRL-F), and type in "Rome - Total War" as shown.
Regedit will find the first match.
Look at the Parent Key, and if it is relevant, delete it.
Use the F3 key to keep searching until the whole registry is done.

1-29) Cleanup.  Now you need to search the registry for 4 patterns:  
        DB158DBF91FB (does it match 4089999C-6CB7-4F9D-A2F6-DB158DBF91FB ?) 
        13C8F3D38C43 (does it match B6BB246A-D1AC-2414-D84D-13C8F3D38C43 ?)
        318C3F3DC834 (does it match A642BB6B-CA1D-4142-8DD4-318C3F3DC834 ?)
        9FE8B7391CF9 (does it match A5D65411-8E73-4C85-AD80-9FE8B7391CF9 ?)
        "Rome - Total War"
1-30) Delete the related Parent Keys associated with each relevant match.

What is a "Parent Key"? It is the related key that contains relevant RTW or Activision or Sega or The Creative Assembly data.
The keys that have long numeric names (called CLSIDs) in the Install/Installer/Uninstall-related parts of the registry are the ones that frequently cause re-install failures.

What to look for when deleting a RTW-related key.

1-31) A "Rome - Total War" entry should not appear in Control Panel - Add/Remove Programs
1-32) If the RTW install process later attempts to Uninstall RTW first, then you need to repeat 1-29 thru 1-31. 
1-33) Close the registry editor

---- STEP 2. Remove the game files ----

2-1) Double-click My Computer.
2-2) Double-click the C:\ drive.
2-3) Double-click Program Files.
2-4) Double-click Total War
2-5) Right-click on the Rome: Total War folder and choose delete.

---- STEP 3. Remove the RomeTW.ini file ----

3-1) Click the Start - Find (or Search) - Files & Folders
3-2) Search your C:\ drive for a file called RomeTW.ini
3-3) Delete the RomeTW.ini file (it should be in C:\WINDOWS, e.g., C:\WINDOWS\RomeTW.ini)

---- STEP 4. Remove the Installer files ----

4-1) Set folder display otions to show hidden folders and files 
4-2) Explorer - Tools - Options - View - Choose "Show Hidden Files and Folders"
4-3) Explorer - Tools - Options - View - UNCHECK "Hide protected operating system files"
4-4) Navigate to folder (it is normally hidden) C:\Program Files\InstallShield Installation\
4-5) If present, delete folders called
C:\Program Files\InstallShield Installation\{4089999C-6CB7-4F9D-A2F6-DB158DBF91FB}
C:\Program Files\InstallShield Installation\{B6BB246A-D1AC-2414-D84D-13C8F3D38C43}
C:\Program Files\InstallShield Installation\{A642BB6B-CA1D-4142-8DD4-318C3F3DC834}
C:\Program Files\InstallShield Installation\{A5D65411-8E73-4C85-AD80-9FE8B7391CF9}

4-6)  Navigate to the folder C:\Windows\Installer\
4-7) If present, delete folders called
C:\Windows\Installer\{4089999C-6CB7-4F9D-A2F6-DB158DBF91FB}
C:\Windows\Installer\{B6BB246A-D1AC-2414-D84D-13C8F3D38C43}
C:\Windows\Installer\{A642BB6B-CA1D-4142-8DD4-318C3F3DC834}
C:\Windows\Installer\{A5D65411-8E73-4C85-AD80-9FE8B7391CF9}
4-8) *Reboot* your machine (needed to remove the files loaded at boot/RTW start!)
4-9) Check for a "Rome - Total War" entry in Control Panel - Add/Remove Programs; if it appears, repeat 1-34 thru 1-36.
4-10) If the RTW install process attempts to Uninstall RTW first, then you need to repeat 1-29 thru 1-31, or possibly redo this whole procedure.

Note 09: Codecs -- RTW needs to have the codecs of WMP9 or WMP10 fully installed and functional (naturally, you also need a working sound card and good drivers). With Windows XP, if you suspect there is a problem with codecs (e.g., you may have installed other codecs and messed things up), then you might want to uninstall WMP10, then reinstall WMP10 if you suspect you have any codec-related problems. Ideally, you should uninstall WMP10, then reinstall it (purely to get the correct codecs installed an properly registered) before you make a clean install of RTW.

Note 10: You can download the WMP10 install for XP driectly from Microsoft for free:
http://www.microsoft.com/windows/windowsmedia/mp10/default.aspx.

Note 11: You can now do a clean install (normal or desktop).

Note 12: If RTW installs successfully, then you have done this procedure properly.

Note 13: If you are unclear about a step, post verbosely. Do not just keep repeating this procedure if you know you followed each step properly.

APPENDIX: These are the registry keys which Step 1 removes (including all key contents):
HKEY_CURRENT_USER\Software\TheCreativeAssembly
HKEY_LOCAL_MACHINE\SOFTWARE\The Creative Assembly

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion \Uninstall\{4089999C-6CB7-4F9D-A2F6-DB158DBF91FB}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion \Uninstall\{B6BB246A-D1AC-2414-D84D-13C8F3D38C43}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion \Uninstall\{A642BB6B-CA1D-4142-8DD4-318C3F3DC834}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion \Uninstall\{A5D65411-8E73-4C85-AD80-9FE8B7391CF9}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion \Uninstall\InstallShield_{4089999C-6CB7-4F9D-A2F6-DB158DBF91 FB}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion \Uninstall\InstallShield_{B6BB246A-D1AC-2414-D84D-13C8F3D38C 43}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion \Uninstall\InstallShield_{A642BB6B-CA1D-4142-8DD4-318C3F3DC8 3 4}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion \Uninstall\InstallShield_{A5D65411-8E73-4C85-AD80-9FE8B7391C F 9}

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion \Uninstall\InstallShield Uninstall Information\{4089999C-6CB7-4F9D-A2F6-DB158DBF91FB}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion \Uninstall\InstallShield Uninstall Information\{B6BB246A-D1AC-2414-D84D-13C8F3D38C43}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion \Uninstall\InstallShield Uninstall Information\{A642BB6B-CA1D-4142-8DD4-318C3F3DC834}
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion \Uninstall\InstallShield Uninstall Information\{A5D65411-8E73-4C85-AD80-9FE8B7391CF9}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Features\40899 99C6CB74F9DA2F6DB158DBF91FB
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Features\B6BB2 46AD1AC2414D84D13C8F3D38C43
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Features\A642B B6BCA1D41428DD4318C3F3DC834
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Features\A5D65 4118E734C85AD809FE8B7391CF9

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products\40899 99C6CB74F9DA2F6DB158DBF91FB
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products\B6BB2 46AD1AC2414D84D13C8F3D38C43
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products\A642B B6BCA1D41428DD4318C3F3DC834
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Installer\Products\A5D65 4118E734C85AD809FE8B7391CF9

HKEY_LOCAL_MACHINE\SOFTWARE\SEGA\Rome Total War - patch 1.3

Changes in 1.53 (23Dec2005):
- Reworded 1-30 to make it clear to delete the associated parent keys of any of the five searches

Changes in 1.52 (22Dec2005):
- Added 2 new possible files to delete in step 4 re:
- Renumbered Step 4

Changes in 1.51 (22Dec2005):
- Added Assumptions 12 & 13
- Added Notes 12 & 13 re:

Changes in 1.50 (14Dec2005):
- Renumbered some steps
- Added the search for "Rome - Total War" section
- Updated procedure for reinstall fail possibilities
- Added Patch 1.5-specific keys
- Added some screenshots

Changes in 1.11 (07Dec2005):
- Added Sega key for Patch 1.3 (Step 1-31 thru 1-33) (will not affect most reinstalls until the newly-announced post-1.3/BI patch is released)
- Added quotes around key names for readability in Step 1-05 and Step 1-08

Changes in 1.10 (06Dec2005):
- Rewrite with more detail
- Remove several more registry entries which cause common conflicts
- Numbering
- Delete BI entries
- Add antivirus info
- Add Step 4
- Add Appendix
- Add more description[/whisper]

[This message has been edited by Wartrain (edited 12-23-2005 @ 10:50 AM).]