Hyper-V Program Manager
We recently published KB2000048 which outlines that if you try to run a Windows Server 2008 virtual machine, with beta integration components, on a Windows Server 2008 SP2 system – the virtual machine will fail to boot.
Ordinarily this would not be a big issue, but the real concern is that any virtual machine created with Windows Server 2008 RTM install media will automatically have the problematic beta integration components.
The best way to avoid this problem is to ensure that you install the RTM version of the Hyper-V integration components in all virtual machines prior to installing SP2 on the physical computer, and after installing SP2 you should use installation media with SP2 integrated into it to create new virtual machines.
If you cannot do this the article above provides you with a list of possible workarounds.