I'll just quote myself from another thread similar to this:

Issues like these are almost always caused by an Anti-Virus program or a harddrive cleaner of some sort. The short of it is, that your history seems to have been corrupted/deleted. This happens when either of the 2 types of program delete temporary files FM uses to store these records while you have you are running FM with that save open.

Do not let them run scans while you have your save open.
 
Top