I am running windows 7 64 bit, fully updated. I noticed that after NIS runs a full scan the boot disk is marked "dirty." This is shown by "chkntfs c:." So, I set it to run chkdsk on reboot ("chkntfs c: /c") and it does so. [It would anyway, even without setting it to do so]. But, it never finds any corruption with chkdsk. After reboot, the "dirty" bit is reset, and the disk is marked clean. Fortunately, this doesn't take long as I have an SSD.
The mechanical drives and the other SSD are not affected, even thought they were also scanned.
Here is the permalink for my original post https://community.norton.com/en/comment/3450673#comment-3450673. I checked 1.5 years ago and there was still no answer. Since my original post, I have replaced the SSD and updated to the latest NIS.