Hey thanks for your reply,
I can not see the Login screen, the patchers start site is the only thing I can see before it crashes after I push start. The error occurs right after the Gepard shield has finished loading. Then, a white window flashes up for a blink of a second just to disappear again. After that happens, the attached error message appears.
FYI: Before I had this problem, I also had the bug with the missing resolution in my settings, but here I was able to figure it out by myself.
Gepard_Crash_Log.txt