NG 15 hangs at 95% and a couple minutes remaining

I've used NG15 (and earlier) for many years on several desktops without any troubles.

All of a sudden about 2 months ago, the backups stopped completing.   The Progress and Performance dialog box says there a couple minutes remaining and it goes not further-- for days.    Why the problem all of a sudden, I'm totally baffled.

I'm running:

  • NG 15
  • Windows 7 Ultimate - 64-bit    (updates are current)
  • 2 Tb hard drive with two partitions (C/D) with the backup backing up C: to D: and then copying the result to a NAS with 6 Tb raid 1 array.
  • Job includes C: and a RECOVERY drive (Dell) which NG says is needed.   

The current state described on the progress dialog is "Updating History".  

I've tried:

  • Deleting and recreating the job
  • Deleting the history files   (of course after stopping the NG service)
  • Doing an install repair.    (This operation gives two dialogs saying:   "No mapping between account names and security IDs was done."   Only an OK button was present and it was selected.

Any suggestions are gratefully anticipated.

Mel