We once had a guy who was having this kind of problem. Turned out he had three different versions of the program all installed at the same time. Might not have been a problem, but he didn't know what he was doing and somehow the different installs were all "tangled". The environment variables were botched up and looking all over the place for different modules, etc.
After cleaning out all the installations and re-installing a fresh copy of the latest, all was well. I never figured out how he managed to get things so royally jumbled, but he was somewhat notable for such things. Don't even get me started on the disasters he perpetrated while attempting machining...
