My computer went completely black and I ended getting a monitor going to sleep message. I thought maybe since I was reading some info. it just went to sleep mode, but after moving my mouse and hitting every button to bring it back from sleep mode it did not. I then tried to reboot the computer and it does not show anything its completely black. I took a look at the monitor by hooking it up to my lap top and it works, I then took a look at the fans in the back of the computer and they are running. I turned the computer off for about 10 to 15 minutes and tried to boot up again and still no luck. I really don't know what it could be. My computer is a hp and is running windows vista its also about 2 to 3 years. I hope someone could give me some advice on what to do. Hope that I provided enough information.