You may have a registry problem. In Regedit (Start>Run> REGEDIT), go to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall and see if there are any keys there.

If the list is there, try system restore to get it back. If not, you're SOL. Since many programs have their own uninstall, that may be the only way to resolve this.

By the way, if Windows was recently reinstalled, this key will have been cleared and there won't be any entries in the Add/Remove programs.