Two nights ago I realized that our VC 5.7.4 Server wasn't starting any new jobs even though the server was started and a handful of jobs were still running.
Checking the log we started getting this error at 2:16:18 and every subsequent second:
4/9/2012 2:16:18 AM Err thisTimeTick was null in TimePicker
Stopping and starting the server from a client failed to resolve this. Only when we restarted the windows service did jobs then start normally. We haven't had this problem again since then.
It seems like VC was unable to query the time from the machine. This is a bare-metal machine and we use primarily custom time triggers. There is no obvious culprit for the initial error.