My PC which I have never heard problems with is blinking when I turn it on. I flip the switch off on the back and it still blinks. I have to fully unplug it to get it to stop. I bumped it with my chair by accident right before the problem started. It's happened before and never caused a problem. I have no idea what happened, everything inside of it that I can see is plugged in. It switches on for a short time then back off over and over until I unplug the power.