Renaming Normal.dot makes sense, since many settings are held within this template.
One theory I have come across is that Word is more tightly integrated with Internet Explorer. I have on many occasions attended calls where menu bars have been lost in a very similar manner, especially where muliple windows had been opened. Restarting the PC, or resetting the MetaFrame session was usually the cure.
I agree, Dreamboat, there is no fix-all solution for problems with thick-client PCs. It is not clear which operating system this installation is installed on, or if there is an overriding profile-based network.
The point I was trying to make is that editing the registry is ALWAYS a last resort. Microsoft will not support you if you do this. The key you have described is a version control key. It sounds like the installation of Office 2000 failed to put the 9.0 key in, for some reason, if this truly is the fix. I have never seen an occasion where this key is missing - usually both 8.0 and 9.0 are present.
I hope this information is of some use.