New type of game crash started. Just back to desktop, no error, no warning.

Something odd just started last night. Game just went back to desktop. No crash error, no dump, just vanished. Happened to me, I dismissed it. Then it happened to a friend of mine in the same night.

When it happened to me, was just after I loaded the game up, but I didnt hit start yet, was in the steam UI PMing ppl and so. Then when I went back a few mins later to hit start, get to char select, crash.

Friend was in Tavern with us when alla sudden no warning, he crashed out to nothingness.