Thats the problem.
I have two monitors... Both are configurated on VirtualBox... The VirtualBox Guest Addons are installed...
I dont know whats the problem is. I hope you can help me :)
The default configuration at the moment is, that the monitors are mirrored. I mean, all what i do on the VBOX0 Screen, i do on the VBOX1 screen. I cant use different windows on each monitors.
Ah, i got not enough space for the monitors...