So my PC has been shutting itself down a few times while I haven't been on it. It always used to start up fine and didn't give me any error msg at start up. Now, however, the thing doesn't respond in any way. I got the light at the back saying it's getting power, but the button just doesn't respond. When I first pushed it the was some strange sound, kinda like "chirping". Then it stopped and now I'm left with a useless PC. Can anyone help me?