Windows Server 2008 R2 SP1 - Hyper-V ISSUES!
Yesterday Service Pack 1 for Windows Server 2008 R2 and Windows 7 was released for MSDN and Technet members. But! It has a serious consequence. If you are running SP1 RC/Beta on your Hyper-V server (hosting VM''s, using Dynamic Memmory Allocation), you must first disable the dynamic memory, since the VM''s will be removed from Hyper-V when you uninstall SP1 RC/Beta! Luckily the hdd files are still present on the system and thus you can just recreate the virtual machines, and add the old hdds After having installed Service Pack 1 all machines are present and up and running again. :)