Neil,
For what its worth, after some extensive testing, I found that whenever that's an XP machine using the app with other OS (Win2k, 98) etc as servers, the moment one instance of the data files are opened, WinXP will place it firmly in its read cache.
No matter what you do afterwards, the other PCs can't see what u have added (unless they have also appended additional records after your appends) and similarly u cannot see the what the other PCs have added.(unless you've appended additional records after the other PCs).
Now, without disabling read caching, what I'm doing is closing and reopening the tables just before each requery()....
Slow but it works...
Yau