Нашел интересный сайт на английском.
http://groups.google.ru/group/microsoft.public.fox.programmer.exchange/browse_thread/thread/c9bd3cdd9cc13627/67a98aba75432538?lnk=st&q=FoxPro+Transaction+reliability&rnum=9&hl=ru#67a98aba75432538

Цитата.
-FLUSH doesn't work on disks that have an active Write cache, which is common
on Windows 2000 and XP an possibly other Windows versions. This feature can
be turned off but may reappear when the computer reboots.
Tha'ts why VFP in recent versions has added commands like SYS(1104) 'Purge
cached memory' and FLUSH FORCE to overwride the Write cache feature of the OS.