Cycletech, I've checked that before and it's been set to Unlimited since the servers were created. It's only been since last Wednesday that the problems arose.
I've uninstalled Windows updates that were applied and none of them are the problem. I had two servers, out of the 6, that were still working. Some time today, 1 of those has also now stopped working.
I'm at wits end with SEP. I have had nothing but headaches since the first time I started testing it. We should have stuck with SAV 10 and forced Symantec to continue supporting it until they got SEP right.