Sunday, January 31, 2010

Computer reboots every hour at the same time

Most times technicians fix a problem but do not really know the cause. A customers computer was shutting down. The first thing to ask is if it reboots itself or does it just shutdown completely. In this case the computer (A Vista machine) restarts. If a computer shuts down completely then it is a hardware issue. If a computer restarts then it is probably a blue screen (BSOD) that flashes by too quickly to see.
To investigate the blue screen the first thing we do is look at the system event log. The log most times captures the stop code of the failure. A good reference for all stop codes is http://aumha.org/a/stop.htm. Also we go into the system settings to stop the automatic restart. This lets the bluescreen remain on the monitor long enough to get some details and hopefully point to a file that is causing the problem.
In this case there was unfortunately no event log item for the failure just a note saying that the last shutdown was unexpected. What was interesting though was that the failures occured hourly at 43 minutes after the hour. this definitely looked like a software issue. I then checked the scheduled jobs for an hourly job without luck. I then looked at the power settings (Vista doesn't have a good relationship with recovering from standby mode) but there was no hourly settings. I even rang the supplier of the software on the computer and they didn't have an hourly process.
As it looked like it was an hourly setting, I just did a system restore back to a time prior to the failures occurring and the problem has so far disappeared. My guess at the moment is a virus but unless the problem reappears I'll never know.
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