Just got a call from a systems administrator who applied Microsoft Patch 2744842 on his vCenter Server 4.1.0 U3 / Windows 2008R2 and ran into some issues after that. You might want to think twice before applying this new Microsoft Patch without proper testing. As you know this MS patch fixed some issues with Internet Explorer. After asking around on twitter if anyone else has had these issues, I got confirmation of only one more incident.
In one case the symptoms were that SOME hosts still show connected in vCenter, but when clicking the hosts tab at the cluster level, they don’t report any cpu or memory load and neither is the uptime reported. It was also noticed that DRS kept moving VMs between hosts who did report correct cpu and memory load.
Unfortunately I am not able to do some tests right now to confirm this issue, so if you have run into this issue or if you have NOT run into this, please let me know in the comments.