I have a 3 year old Dell Dimension E510 desktop that has worked fine until now. I shut it down when I went on vacation. I've tried to turn it on by pushing the power button, but the cpu won't turn on. A yellow light flashes every 5 seconds or so. It's been a long time since I turned this computer off and I'm stumped. Any ideas?

Unplug the power cord from the back of the computer and let it sit for an hour or so. Then plug it back in and try booting again.

Fingers crossed.