Recently, after running CFS3 without a hitch for years, I've experienced a similar problem with the game closing after very short periods of time to the point that I can no longer run the sim. I get an APPCRASH message and the game closes. It is not a fan or cooling issue and only involves CFS3 offshoots (OFF, MAW, etc.)
I've posted here (See, "Help, Please!" thread), but although lots of people have tried to help, absolutely nothing works. I run Vista, but I don't know if that is the issue. The problem surfaced in mid-July. I thought it might be caused by some Windows update, but that hasn't yet proven out.