Citrix wont uninstall: Windows Installer Service fails.

Microsoft no longer supports the Windows Installer Cleanup Utility. Try this tool instead.

Revo Uninstaller
http://download.cnet.com/Revo-Uninstaller/3000-2096_4-10687648.html

How about to reinstall Citrix ICA Client? The Windows Installer fails to launch.

I can't imagine for it to not be possible to fix Windows Installer.

Step 1: Check the Windows Installer Service.

1. Click Start Orb, in the start search box, type Services and press Enter.
2. Scroll down and find the Windows Installer.  Double-click “Windows Installer” in the Services list.
3. On the General tab, make sure the service is started under “Service status”.
4. If the service is not already running, under Service status, click Start, and then click OK.

Step 2: Unregister and re-register the Windows Installer
1.  Click Start Orb, in the start search box, type MSIEXEC /UNREGISTER, and then click OK . 
2.  Click Start Orb, in the start search box, type MSIEXEC /REGSERVER, and then click OK . After you run this command, the operation is complete.
3. Now, try your installation again. 

Step 3: Clean any pending installations
Check the following registry key and clean any entries in the key that you find:
Go to the Start Orb, type in Regedit and select enter.
If you get the User Account Control dialog box that states, Do you want to allow the following program to make changes to the is computer?, Click yes.

Modifying REGISTRY settings incorrectly can cause serious problems that may prevent your computer from booting properly. Microsoft cannot guarantee that any problems resulting from the configuring of REGISTRY settings can be solved. Modifications of these settings are at your own risk.

Scroll to: HKEY_LOCAL_MACHINE \Software\Microsoft\Windows\CurrentVersion\Installer\InProgress

Check the following registry key and clean any entries in the key that you find:
HKEY_LOCAL_MACHINE \System\CurrentControlSet\Control\Session Manager\PendingFileRenameOperations

Step 4: Check the permissions
Verify the System has Full Control on the following keys:

HKEY_LOCAL_MACHINE \Software\Microsoft\Windows\CurrentVersion\Installer

Next, restart your computer and try again.

If still having problems, then create a new Administrator User account and see if the problem could be a corrupt user account.

Please reply back and let us know if this helps with your Windows Installer Error.

Sincerely,

Marilyn

Error 1719 Windows Installer Service Could Not be Accessed, when installing applications.
http://www.winhelponline.com/blog/misc-registry-fixes-for-windows-7-xp-vista/

Problem accessing Windows Installer Service
http://social.answers.microsoft.com/Forums/en-US/w7programs/thread/ac6e4add-0e62-4ba0-b734-7a1a69872c38

How to Perform an In-Place Upgrade on Windows Vista, Windows 7, Windows Server 2008 & Windows Server 2008 R2
http://support.microsoft.com/kb/2255099

Windows 7 - Repair Install
http://www.sevenforums.com/tutorials/3413-repair-install.html