Usually, when a program cannot be uninstalled, using the program's uninstaller or the Control Panel/Uninstall, the program must be reinstalled to correct the corrupted uninstall information and then the program can be uninstalled.

There are some commercial (pay for) programs that claim they can uninstall "problem" programs.  

Thanks. I'll try that. The reason I want to uninstall photoshop is that I plan to upgrade the OS from Vista to Win7. If I can't uninstall photoshop is it OK to just delete the program folder from c:\program files before upgrading the OS?

Just deleting the folder is only part of the uninstall.  There are "hooks" into Windows and registry entries that will still be there.  

If Photoshop works OK with Vista, it will work OK with Windows 7, thus you wouldn't have to uninstall it.

It depends on the program ... for example, iTunes must be uninstalled before upgrading from Vista to 7, then reinstalled after ... it won't matter with most programs though.  If you run the Upgrade Advisor for Windows 7, it should give you a pretty reliable list of which programs should be uninstalled first or that won't work with Windows 7.

Thanks for the suggestion but I'm surprised you say that it is not necessary to uninstall programs before upgrading the OS. Is this true for most programs? I've been under the impression that most programs need to be reinstalled when the OS is changed

Tecrowley,

You can download the Windows 7 Upgrade Advisor from here:  windows.microsoft.com/upgradeadvisor

Tony