Around 01-18-2017 09:25:59 the profiler PC stopped responding to pings from the data manager, then the pings recovered a minute later. Soon after there were nagios alerts that the profiler data had stopped. I suspect the profiler PC just rebooted for some unknown reason, and after that POP did not restart. (I assume POP is not setup to restart automatically.) Around 19:30 I connected to the profiler PC with VNC and was able to start POP manually, and now all the nagios checks are green again.