Today I heard a new one – someone had configured SBS 2008 on a server, and enabled the Hyper-V role on that server. They had then put some Hyper-V guests on top of it. They installed ShadowProtect on the SBS 2008 server and were experiencing issues with the guest operating systems having their disks disconnected during the ShadowProtect backups.
The long and the short of it is this. Microsoft do not support the Hyper-V role being enabled on SBS 2008 itself. They have documented it here .