Can't start the computer

I got a big problem, i was just browsing the internet as usual when suddenly the computer went into power save mode. It told me to press any key or move the mouse to exit power saving mode. I did that but nothing happens. I got a wireless mouse and keyboard if that matters, i even tried with a wired mouse and keyboard but no luck. So i unplugged all cables and reconnected them and tried to start the computer again but the problem remains. I still get the same message on the screen and then it goes black. I got no idea what to do. I can't enter the BIOS or anything.

This has happened once before but it happened when i was restarting the computer, i went to start and clicked shut down computer then choosed restart(im running windows xp home edition by the way). The pc didnt restart, it went into power saving mode instead and i had the same problem, i couldnt exit power saving mode. However, after i had the pc shut down for a few hours i started it up again and it worked.

But now it's different, I've had the computer shut down for hours now but it still doesn't work when i try to start it. I find it hard to believe it would be a virus since i did a system restore not long ago, and i have a bunch of antivirus programs.

I would really appreciate if someone could help me, i have no idea what to do.

My computer: http://support.euro.dell.com/suppor...al?c=se&cs=RC1059028&s=gen&ServiceTag=8YQZX1J