I have it, but probably haven't ever used it to the extent you have. I just use it to run an ubuntu server virtual machine.
Anything I could do on my system to check?
If you could just reboot and see if it gives you any warning different to normal windows! Pretty sure I didn't now, though, think its something else.
Reboot the Windows Server? Or reboot the Hyper V VM? I am using Hyper V on Server 2008 R2 rather than a system just running Hyper V (if that's even possible?).