I'm not sure what the problem is, but here is what you can try to debug the problem.
Have you tried some sample slick web start from the website. If they work then you are simply trying to set a invalid resolution. The display size appears to be correct, but perhaps your bit dept is not support.
I know that some video card do not support certain refresh rate/bit dept/resolution combination. Try experimenting with the permutation and changing the window' resolution as well.
Tue Apr 21 15:04:41 CEST 2009 INFO:OriginalDisplayMode: 800 x 600 x 32 @75Hz
Tue Apr 21 15:04:41 CEST 2009 INFO:TargetDisplayMode: 800 x 600 x 0 @0Hz
I tried 16x bits and 32x bits, it doesn't work. I can launch without probs the webstart demos.
The card of the virtual machine is S3 Tri32/64, I try new drivers