ESXi 5 to ESXi 5.1 upgrade problem

Hi guys,

So, I decided to update one of my ESXi hosts (not in production yet) to 5.1.0 from 5.0.

Immediately, there is a problem when trying to power up a vm based on Windows 2008 R2 server, the error is:

Failed to start the virtual machine. Module FeatureCompatLate power on failed.

There seems to be a reported issue of the upgrade, see here:

http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&ved=0CDQQFjAC&url=http%3A%2F%2Fcommunities.vmware.com%2Fblogs%2Fvmwaretam&ei=sYuTUJ7SLsOQ0AW72oH4Cg&usg=AFQjCNGiVhliDn1Tkg866rY5A7y17xeg_Q

I'm keen not to do the updrade on the other ESXi hosts until I resolve this one.

I dare say downgrading might be a good idea?

Thanks in advance for any advice!

Hesan