So you checked "disable ultrapeer" and it's still quitting on you? Hmmm. Maybe it's only a coincidence that it's stopped crashing this evening for me after I took that step. We'll see. It's funny though, it worked for another person having the same trouble. Are you sure you applied the change by clicking on the apply button?
Well, the good news is that the LW folks eventually get it right—2.5 should have a fix for this problem. Hang in there.