Don't install the new win7/2k8 "convenience" update

Unless network connectivity isn't important on your machines using VMXNet3
RUSH POST: Microsoft Convenience Update and VMware VMXNet3 Incompatibilities - Virtualize Business Critical Applications - VMware Blogs
RUSH POST: Microsoft Convenience Update and VMware VMXNet3 Incompatibilities - Virtualize Business Critical Applications - VMware Blogs
Comments
"Simplify, then add lightness" -Colin Chapman
Although it didn't just jack up vms it also messed with physical 2008 servers as well, installing a new adapter and setting it to dhcp.