Split screen

[Bobb4]

I have a split screen when playing tracks, the top half shows the sky and the bottom half is black.
If i launch a single player mission the problem does not exist.
The problem only arrived after installing the patch plus hot-fix.
I also cannot connect to any online games.
I get stuck at waiting for battle to start screen.
This is all post pre-release candidate patch.
I have verified the integrity of my install with steam and re-installed the patch.
Nothing changes
I have a HD6950 graphic card and I am starting to wonder if the game thinks I have crossfire enabled?
The game ist totally not playable at the moment unless I restore to pre-patch steam or the previous beta patch.
Any ideas?