No encrypted HDD, no NAS, and antivirus already excludes the Armory folder(which cotains both ADB and Bitcoin blockchain) due to some well-known trolling events where ppl deliberately included transaction bytes to resemble malware and flag false-positives.
I've used McAfee AV some time ago. Previously everything worked pretty well, but all in a sudden I've gotten corrupted files and crashes of ArmoryDB. I also tried to set folder exemptions, but it didn't really prevent these errors from happening. So I've tried to deinstall my AV and gotten rid of all of my AV services (except Win Defender) and then it worked like it should.
But I have to admit it was hard to drop something that's already paid in order to get Armory running. So I can't tell if that might solve your issue, but again it looks pretty similar to mine.