My copy of ETW (got via steam) has worked with problems until tonight, now i cant host games online i get the message "unable to host game".

Also i am unable to join the vast majority of games, even if they ahve spare slots,the screen goes slightly grey for around 5-30 seconds then it drops back to the normal games screen.

Many games are also in red saying a "different game version" is running?
Is this pertaining to the patch? my version has already updated..

So why cant i host games?