My Crysis 2 MP freezes after any map change.

The map finishes and I see a black screen and my CPU is at 100%.

I need to kill the process in the taskmanager.

My Rig:
E8400 @ 3,8ghz (No, it's completly stable since 2 years )
HD4850 512mb
1 TB HDD
Asus P5K

Playing with 1920*1200

Thanks for reading.