A few times, when developing levels, the 3.6.10 RC2 FRED2 too crashes on me when saving and corrupts the level being worked on, making it unusable in both FRED2 and in-game.

I'm wondering if anyone has had the same issue. As precaution, I'm backing up my levels everytime a small part of any of my levels are made.

Bear in mind that both the .bak and the .00x files can be used to recover from corrupted missions as they are simply renamed older versions of the mission.

As for the crash, if you are using RC3 look at this.