I've had it put us in a Versus game when we were supposed to be in a regular game on normal difficulty.Yeah, I've had that several times... VERY annoying.
I do not recommend ever alt-tabbing from a valve game. They just don't take it well.I know but it's disappointing. I really hope Windows 7 tries to improve alt-tab performance as it should be instant - a game should alt-tab exactly like Firefox or Outlook (the fact it's using 95% of the CPU should have no bearing on that performance). Windows should always take priority so you can properly manage applications / deal with unresponsive applications. Vista improved things considerably but there's still a LONG way to go.