"what is telling you it is the Quick Scan running?"
Okay, I wasn't able to verify it was QuickScan that's been running -- I was assuming it still was the culprit based on previous experence. Upon examining the Check Security History > Full History, I was unable to determine what it is that's actually running. But something is running/scanning like clockwork and I can't figure out what it is. Auto LiveUpdate is disabled and no other scans are scheduled. However, the PC TuneUp options for Diagnstic Report and Startup Manager will not allow me to disable/uncheck their boxes. The aforementioned tuneup tasks display last run dates which do not coincide with whatever NSS is running regularly on this machine. The only options that are remain checked on the Settings > Quick Control are: Smart Firewall and Norton Tamper Protection. I've also checked the Get Support to see if there are problems with the installation, but it displayed that no errors were detected.
"I would also suggest selecting Perfomance form the main paghe, let it flip and on the bottom chart, select CPU and you will be able to see what is being used by NSS (yellow) and what is being used by the rest of the system (blue). "
"check to see if there are any other security programs installed"
Performance Monitoring is disabled because I exclusively use Windows Task Manager for that purpose. But I'll re-enable this Norton feature the next time I notice this unknown process is running in hopes of identifying what it really is. Lastly, there are no other antivirus, antispyware, or other security programs installed on this machine that would lead me to believe it was anything other than NSS running. At this point, I'm baffled at what Norton is doing that continues running at a regular intervals. I don't have the patience for this software anymore and feel it's better to just pay for a different antivirus program that allows me full control over it, rather than keeping this free Norton/Comcast product which runs according to its own unadjustable settings.