Sounds like something has overwritten the uninstall program. Perhaps some sloppily coded add-on?
Try putting the first CD in and trying to uninstall from the setup options that appear when the CD loads. If that doesn't work, you could probably just reinstall over the top, then try uninstall afterwards - bit long-winded though.
If that fails, you'd have to hack all the references from the registry and delete all the files manually to get a clean uninstall. That's a road you should only go down if you're reasonably experienced at registry editing mind...