Q: Lately my iMac has been shutting down by itself. When I attempt to turn it back on, sometimes it does normally, other times it will only after I disconnect the power cord from the back of the computer and then reconnect.

My imac is shutting down on its own. Sometimes it will start when I press the power button. Other times it will only start after I disconnect the power cord from the computer and then reconnect.  Could this be an issue with the power cord or something more sinister?  I haven't heard anything about power cords going bad.  Any information would be helpful.