Hi Eugen,

In my experience there are a few things to check:
*forced writes - As Adam said ensure forced writes is on to ensure when
there is a problem there is less chance of getting a corruption.
*Power/UPS failures - This is generally where I see most of our
corruptions
*Harddrive errors
*Windows Suspend/Hibernation (can't remember which one it was)
*Backup processes/virtus guards/any thing that tries to use/lock the
physical database file
*Copying the database whilst FB still has a connection to it (keep in
mind that even if all the clients are disconnected FB may still be busy
with the DB in the background, hense Adam's comment to stop the FB
service)

Take a look at:
http://www.ib-aid.com/option,com_content/task,view/id,58/Itemid,62/

Regards
Thomas Ellis