When I turn on my PC, the external hard drive (Hitachi) won't power up. I can get it to power up if I unplug the power cord and plug it back in. However, if it stays idle for awhile (15 minutes?), it will shut down again. It is about 5 or 6 years old so should I just get it running and copy to a new external drive or waste time trying to figure out what the problem is?