In Family Treemaker - not UFT - errors and system hangups started occuring for users who had upgraded from Word97 to Word 2000. This was eventually traced to (blamed on) Script Blocking in the then current version of Norton Anti-Virus 2000 or so. FTM did not have proper error trapping, and the program would crash.
Turning off Norton AV seemed to eliminate the problem in FTM.
At that time I posed a query on the UFT forum, but it appeared no UFT users were experiencing similar problems. However, the power UFT users were consumed to switching to TMG at the time and might not have noticed.
There was one other potential problem with Word 2000 registry that affected other applications. As I recall, MS changed its long standing policy of numbering its "application library" identically wit the MSWord version number. Thus the MSWord 97 v8 library was retained in MSWord 2000 (v9 or 10?). Or something like that. I think it may have caused more problems for Microsoft applications than for others, but the problem was a red herring fully documented in the MS Knowledge base at the time.
Again, no UFT users reported significant problems on this forum with Word 2000 as am editor/server at the time of its release.