I've just restarted my server after installing .NET framework 3.5 SP1 and now I don't have any inforamtion anymore on my VMware servers ( statistics are unavailble )
Our VMware administrator has recently upgraded the Virtual Center from 4.0 to 4.1
Hard to tell just by this information what is going on, I would recommend a support ticket
I'm receiving information again from my VMware servers, but I'm awaiting the response of our Virtual system engineer for the solution he provided