Hi René,
If you can enable logging and restart the VM, that'd be great. Let me know if that would be too disruptive. I assume you will need to follow the same steps as you mentioned above in order to get the VM to boot into Windows when you restart it...
I hadn't noticed Windows Server 2012 using Driver Options before... Interesting. I'll have to take a look at that.
Cheers,
--
Darius