A number of people have experienced issues after installing the July 2013 Update Rollup. Some of you were quick to comment on my post (thank you for sharing) and more comments were posted on the TechNet forum.
The issue appears to affect people with a common configuration: a virtual switch connected to a NIC team, and multiple VLANs being supported. No; I don’t know how this slipped through testing. Yes; Microsoft are aware of the issue.
Please do not install KB2855336 until further notice.
An alleged fix was included with an updated version of the July 2013 update rollup.