Today November 30th DotA 2 has caused over 40 crashes between both my friend & I AFTER we Party up and search for a game together. He will crash to Desktop, or I will crash for no reason. There is no time element involved, it's totally random, but often between 5 and 50 seconds.

On our own, we each join a game no problem. But when partied together, DotA 2 kicks us from both being partied.