High Disk Write - distrptr.dat

For a few days, Windows 8.1 PC is slow, near the point of not being useful.

Task manager and/or Resource Monitor show hard drive C: frequently at 100% utilization and very slow response time.

It looks like every second, there is a spike of about 2 - 4 MB/sec write.
It appears to come from NIS  diStRptr.dat and diStRptr.log.

C:\ProgramData\Norton\{0C55C096-0F1D-4F28-AAA2-85EF591126E7}\NIS_21.0.2.1\diStRptr\diStRptr.dat    0 2,721,006 2,721,006 Normal 5

It looks like I am on a current version:

Any thoughts on a resolution?

 I did reboot and then manually (via GUI) run update to get the software to update as well as the known virus file.
Update appears successful, yet problem returns minutes later.