Mike,
Symantec release notes says, that it was a know issue and was fixed with the release of MR4 MP2,
http://www.symantec.com/business/support/index?page=content&id=tech103087
I’m running win server 2008 R2 and Win 7 with SEP 11.0.6 MP1 clients and I don’t seem to have these problems....
If I were you and wanted to spare some time to dig into it,
Then I will make sure the clients throwing these error messages, are not running multiple AV programs, Disable Windows defender as that’s an AV program of Windows
(Users have the tendency to install Malware bytes n other freeware AV program, if they had the privilege).
If you are using NTP of SEP 11 disable it.
If you are not using NTP, disable Windows firewall.
Regards
Karthik