Hi again John - trust you got my previous message about updating the runtime.
Now, I've read the rest of the thread and I don't have a solution - but for whatever reason it sounds like VFP has decided internally (at the user machine level) not to optimise the query on those user machines. I've seen that happen from time to time on large data files. The differences in query time are too big to put it down to network performance, NT vs Novell and all that stuff.

Ok - that's not much help, but then, it just could be the version of Foxpro, as you suggested; it is consistent with the difference between machines. Has the data size been increasing? Are there lots of deleted records building up in any of the tables. In my experience, deleted records are notorious for turning the optimiser mechanism off completely and Fox does a sequentially search/join resulting in *huge* temp files.
Lotsa luck