I also have freezing problems. When the freeze occurs, Windows will notify me of a re-initialized video driver. The freeze can be 5 seconds or 1.5 minute. If it takes long I will time out on the server, but I won't have to close the game cause it will respond again after that short period. When it freezes the screen goes black and the sound loops. This is different from the more "common" problem, because my game actually responds again after X seconds. I will try the mat_queue thing anyway.