Endpoint Protection

I don't have 100% proof, but we recently started experiencing some VM servers hanging (it seems to be working, but one can't logon interactively to them and WMI scanner reports connectivity errors). The only change recently was installing of SEP 14 MP1 client (Basic Protection for Servers) over the latest 12 version. Currently i had two 2012R2 servers hanging once per week (they are on the 2012R2 host which also received SEP 14). And one WS2008R2 which is hanging every few days, which is on WS2012 Hyper-V host with SEP 12 for now (VM is on SEP 14). I don't see anything in the Event log. These machines were running smoothly for half a year with SEP 12.

Are you on SEP 14 MP1? Also, what components are installed? See this KB to see if it fits your problem description:

http://www.symantec.com/docs/TECH236543

As i've said in the post, yes, we are using 14 MP1 on the servers. Thanks for the link. It looks similar. But it's strange that the issues started for some servers only a week after the installation (maybe definitions update caused that). I have another suspect though. PRTG Network Monitor has been updated on 05.17 and first hang occured on 05.18 and from that point we had 1-2 hangs per day. I have disabled PRTG for now to see if it changes anything.

Ok, PRTG wasn't the cause as a few servers hanged while it was disabled. We are now reverting to 12 version on the servers. It's strange that now desktops were affected so far.