Hi Alantor,
It appears you're using a dual-GPU configuration. Dual ATI Mobility Radeon HD 4870/5870 to be specific. Luckily, you're not the only one experiencing this issue. It's been reported a few times by other users with similar multi-GPU configurations. Disabling CrossFire should allow you to play without the freezes, though potential performance will be reduced as a result. Also, it would be great if you could open a support ticket so the devs can collect additional information on this issue.
-Exhumer