Hi guys,
Only just noticed that this thread had replies!
I managed to solve this issue in Arc9.2 by carrying out a complete clean reinstall. This solved the issues relating to 3D analyst, however issues with graphs remained. I solved these by deleting the Normal template and getting ArcMap to reconstruct it, this seemed to solve this one.
I can't comment on what might help 9.3 or 10 users I'm afraid, still stuck in the dark ages! 😄
Ed