Here's a quick jumpstart for you when you are in Hyper-V troubleshooting mode:
(950050) - Describes the update to the release version of the Hyper-V technology for Windows Server 2008.
(952627) - Describes the Windows Vista Service Pack 1 Management Tools update package for the release version of Hyper-V.
(954279) - Discusses a problem in which you are not prompted for credentials after you receive an "Access Denied" error message when you try to connect to a virtual machine from the Windows Server 2008 Hyper-V MMC snap-in. Provides a resolution.
(951308) - Discusses the increased functionality and virtual machine control in the Windows Server 2008 Failover Clustfer Management console for the Hyper-V role.
(947725) - Describes an issue that may occur when the CNO of a destroyed cluster is not successfully removed from Active Directory.
(950792) - Describes a problem that occurs when you try to enable, disable, or update Hyper-V technology on a Windows Server 2008-based computer. The resolution is to rename the Cpqteam.dll file and then to try again.
(949222) - Describes an issue in which a virtual machine cannot start. To resolve this issue, you must delete all virtual machines that have the beta version of Hyper-V. Then, re-create the virtual machines.
(953828) - Fixes a problem that occurs when a Windows Server 2008 virtual machine is running in the Hyper-V environment on a Windows Server 2008 host computer.
(954958) - Describes the server and client guest operating systems that are supported on a Hyper-V virtual machine that is running on a Windows Server 2008-based computer.
(954418) - Describes that sleep and hibernate power features are not available when you enable Hyper-V technology on a Windows Server 2008-based portable computer.
Still having trouble? Don't forget to try the Hyper-V forum: http://forums.technet.microsoft.com/en-US/winserverhyperv/threads/