[Crash] Unkown DirectX error.

The game crashes after champ select but before loading screen with an "Unknown DirectX Error".

To recreate simply attempt to join a match. It occurs about once a day but not for every match. However, if I attempt to reconnect to the match the error will occur again.

I reinstalled my drivers and repaired the client but it still happens roughly once a day. Interestingly it doesn't happen on the first match of the day, or even at the same time of day. It appears to be random. Maybe once every 20 matches.