As part of the 14 security updates preying on Microsoft customers this month, there's been whispers of some problems. One problem, which I'm still waiting to hear the extent of before reporting fully, is in a reissued update for the SHA-2 weakness. Apparently, this update is causing systems to enter into a reboot loop. I've heard a few reports that say it's catastrophic, but the issue may be affecting only a small percentage with very specific configurations. If this is affecting you, let me know.
One issue we are positive of right now, though, is with MS15-027 and EMC Isilon OneFS storage systems. Microsoft's own KB article, MS15-027: Vulnerability in NETLOGON could allow spoofing, details the issue, the cause, and a possible workaround. But EMC is recommending not installing this update until the company can release a patch, which is in development right now.
EMC has a technical advisory posted HERE, but it requires a customer login to read.