This question comes up, oh, every second day. The usual solutions are posted, oh, every third day.
While you are waiting for a more patient person to respond, you may like to search the forum. It won't take long to find any number of posts discussing this well known SH3 problem.
Here's one thread on the subject...
http://www.subsim.com/radioroom/showthread.php?t=93381 (my post explains).
I've never ever had the problem, prolly because I *never* save mid-patrol.