I have found a "fix" for this freezing.
When ever you are searching for a for a room in player matches, and decide to search again, try this. Hit back all the way up to where you can select a ranked or player matches, select ranked then quick match and quit before it ever loads up. Then you can go back to searching for player matches. This works for me EVERY time, as long as I don't try to be lazy. 8)