Steve,
It is possible that your installation has become corrupted. The way to take care of that would be to delete the program then shut down everything on the task list except Explorer...(msconfig works great for this if you have Win98, type msconfig at the
RUN window) make sure any anti-virus is shut down, then reinstall. I've see this happen before, and usually if you just go ahead and bring up the Symbols Explorer (Draw>Symbol>Explore, I believe) then manually pick one of your .slb's , it will find them in the future. There is a path in the registry, but this method should work....
Thanks !!
Rob Bradbury
PSG Product Support, Americas
WW Support & Services, Autodesk
Discussion Q&A: http://www.autodesk.com/discussion