At about 16:42 UTC, I found the IRIG-B timing was off by more than 65000 on h1iopsusb123, and all user models had stopped running.  Not sure what the cause was, a minute trend of the IRIG-B time showed it went bad about 16:23 UTC.  I killed the user models (h1susitmx, h1susbs, h1susitmy), and restarted the h1iopsusb123 model.  It came back in a normal state, so I restarted the user models.  All is running OK at this time.