I and a bunch of others are having this problem. Seems to have become much more problematic now. I didn't have this issue but once or twice prior to v4.4. I somehow got it to go away after messing around a bunch but now that I went through the dungeon across the bridge it's come back and I crash every minute or so... others who work with UE4 mention its not a 'crash' because the engine knows what's wrong and it has to do with something improperly compiled in the code. Another thing they mentioned is it could be due to memory fragmentation due to the broken code...
I hope Digitalfurbelow sees this and can find the issue and put out a hotfix.