The Graphiccard is actually a ATI Radeon HD2600. A Monitor with a resolution of 1920x1200 is also connected at the primary Port.
I also tried the Setup on my MacBook Pro with a GeForce 8600M GT inside and get the same problems on accessing Fullscreen Mode.

It dosen't matter if i'm running in Headlessmode or not. The System will crash in both Situations.

Posting Showfiles is a littlte bit difficult. At the Moment there is only a Modem Connection available.
I try to post a crash report as soon as the system will crash at the next time.