[ubuntu] Windows 7 Guest crashes to blue screen on startup

host: ubuntu 12.10, 64-bit
Guest: Windows 7, 64-bit
platform: Virtualbox.

I copied a working virtual machine from windows to Linux, but it never started. it crashes to blue screen after the windows logo.

do you know any known issues that can cause that ?


i7 3612qm with VT-x enabled.

Thanks