The only thing I've found that works is to pause when it starts to lock up, then esc and press start recording on the menu that appears. Then back into game, press esc and then stop recording and back into game, unpause and continue. This is the only thing that works for me and the problem does not reappear in that mission thereafter, up to 90mins, (109 stops flying around this time, lol!). You'll need to do this for every mission you suspect will be a long one. (30mins+)
It is a bug that's been around since 4.09.1m, some claim it's hardware, overheating, bad memory etc., but despite extensive testing, swapping components etc., I've not found it. It's not bungling bill's crap software either as far as I can tell. It appears to me to be something to do with trk recording causing memory overflow, for some reason Bessarabia and the Slovakia maps are prone to this.
I've only recently discovered this "solution", and haven't flow many long missions recently, but can say this works on eastern front maps. Maybe DT will give us a button to turn off the default trk recording altogether as a stop gap to this problem? Hope this helps
