Have you verified in the Mcafee console if a sheduled system scan is running?
That might cause this issue.
The task might be configured to "run missed task"
Could you help clarify a few things? For example you said:
>> consistantly scanning drives and folders (sic)
That is what VSE is supposed to do. So how exactly do you come to the conclusion it is scanning things? What tool are you using? Did you use the McAfee Profiler tool to see exactly what it was scanning? Or did you use some other indirect method? What was observed? What is it that you think shouldn't be scanned? Concrete examples here would help. Output from the McAfee Profiler tool plus a screenshot of the On-Access Defaul policy's exclusion's page would really help us a ton.
>> causing machines to grind to a hault (sic)
Again, could you be a bit more specific? I assume there's not an actual grinding noise and that the machine doesn't fall to Zero MHz. The disk LED is solid? You notice a program in task mgr doing ____? CPU utlization is doing ____? You used the tool ____ and noticed ____?
We'd love to help but we need something a bit more to go on.