THE OFFICIAL BLOG OF THE SBS DIVA

http://technet.microsoft.com/en-us/library/gg563799.aspx#BKMK_SynchronizeTheSourceServerTimeWithAnExternalTimeSource

Show me a failed migration from a physical box to HyperV and I'll show you a time zone/time sync to an external source problem.

The installation of Windows Small Business Server 2008 on a Hyper-V virtual machine fails if the time zone of the virtual machine differs from the time zone in the parent partition:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;956359

The problem is no different for SBS 2011.  It is so very very very key that you ensure that both the source server and the built migration server are exactly in time sync.  The reason is that Active Directory cannot replicate (talk to one another) if the time zone of the two machines are plus or minus 5 minutes apart.  This is a key Kerberos requirement and you'll have a barfed install if you have a time problem between the two servers.

I have personally found that the documents recommend that you do NOT enable the time integration in the hyperV, but instead ensure that the DC in a HyperV syncs with an external source.  And here's the rub... then I've found the HyperV's drift a bit.  So here's my resolution.  I personally found that following these commands on this blog post made my HyperV DC not drift.

Hyper-V, CPU Load and System Clock Drift:
http://jaylee.org/post/2009/10/14/Hyper-V-CPU-Load-and-System-Clock-Drift.aspx

All I can say is...it worked.

But bottom line, there's an EXTREMELY good reason that they recommend you make sure that the time is in sync.