We researched it quite thoroughly after looking for help on UT, and ended up with this handy program that fixes the registry setting (otherwise seach Microsoft.com for info about oplocks and caching - you'll end up with a bunch of registry settings to change, and they're different per OS...)
I've got a link to a program called NONTLOCK.EXE available on our website that makes all the changes for you. Go to
http://www.procomp.co.nz then choose Links.
Some notes I have made/copied from (somewhere)...
Opportunistic Locking
In All Windows O/S including NT, 2000, XP must be disabled to prevent data loss.
see
http://support.microsoft.com/default.aspx?scid=kb;en-us;q296264Microsoft has admitted Win 2K and XP have problems due to Opportunistic locking. It is causing datafile problems with MS Excel as well.
http://support.microsoft.com/default.aspx?scid=kb;en-us;812937&Product=winx
