Sounds like a conflict between installshield and SP2 i have seen before - with a paticular game. You can nsually uninstall the program file folder, then use TweakUi for windows and go to TweakUI Add/Remove tab. then within the add/remove programs tab, select the programs you wish to remove and click the Remove button. Close TweakUI when done.
Alternatively you can do it in the registry *be careful*. Click Start, Run and type regedit, then within the registry, open the below key.
Within the above registry key, select the program you wish to uninstall from the right side of the window. Exit.