Some uninstallers use a log of the install process to 'know' what they should uninstall. So they can't proceed if that file got lost somehow.
The usual solution is to reinstall the program, then immediately uninstall.
If that doesn't work the work-around is to delete the programs folder in Program Files, use regedit to do a manual clean of the registry, and maintain Start>Programs yourself. For 'simple' programs, this can work quite satisfactory. But don't try it with anti-virus or firewall or anything more complex than a 'simple' program!
Hope this helps.
I am trying to rid a few things off my PC. I use Add/Remove but when it tries to uninstall i get a pop-up saying install.log not installed.