I get similar problems working with audio. For me, the signal is that the Split command stops working. I always use Alt - click, but S and the menu also refuse to split clips.
This seems to happen when I'm doing lots of splitting and moving things around to get audio timing right.
I was excited about the History depth suggestion, and I reduced it from 128 to 32. The problems (and the whitescreen crash) seemed to start sooner than before. I tried increasing the Undo depth to 256, since I've got plenty of memory. It took longer, but I eventually got a Not Responding whitescreen crash.