Jonathan, TJ, Dave:

just before noon local h1lsc0 suffered a timing error, reported as ADC timeouts on all the user models. There was no disconnect between the computer and the IO Chassis, so we just needed to restart all the models to recover the system. Note: h1ioplsc0 is the timing master for the h1oaf1 computer. It appears that h1oaf1 rode through the restarts, but if we have any problems with this machine's models tonight we may need to consider restarting them.

The timing glitch is most probably related to ISC electronics work which was ongoing at the time.