I had the opportunity to go onsite for a training this week, and when preparing the machines for the training they all crashed when the hyper-v role was deployed. After some investigating we narrowed it down to the video driver, when using the Standard VGA driver everything worked, but as soon as we added the (Intel) video driver - the machine crashed.
These were Intel i5 CPU machines, and we already had the 975530 hotfix deployed (needed for i5 and i7 CPU's). But we still got the crash.
SP1 (beta) for Windows Server 2008 R2 solved the problem, and we had no issues for the entire training,,,