Hello,
In SEP 12.1 and later versions, IPS kernel driver (idsxpx86.sys for 32-bit and idsvia64.sys for 64-bit systems) is installed and running with Advanced Download Protection feature (aka Download Insight).
In your case, I would request you to check these Articles below:
Best Practices for employing Intrusion Prevention System (IPS) to high-availability/high bandwidth servers.
http://www.symantec.com/docs/TECH162135
Windows Server 2008 x64 Crashes with Symantec Endpoint Protection 12.1 client installed with DRIVER_IRQL_NOT_LESS_OR_EQUAL (d1)
http://www.symantec.com/docs/TECH199657
Secondly,
I would request you to uninstall SEP 12.1 RU1 MP1 and then reinstall SEP 12.1 RU2 on it.
By reinstalling the SEP 12.1, it would then create exceptions for Exchange 2010 which may help eventually.
Hope that helps!!