Windows 7: Problem with Sleep?

Hey everyone,
I happened to be streaming some media to my PS3 from my desktop when it decided to go to sleep. I knocked the mouse to wake it up before it had shut off (the display had turned off ten minutes before) and it wasn't happy.
The display did not turn back on for half an hour though the computer never fully went to sleep either. I eventually hard reset.
The computer turns on for about three seconds, powers off, then powers back on as if it was completing sleep mode and waking up. But no display ever appears.
Not sure what to do at this point, wondering if I have to manually remove the session data that was stored to HD somehow.
Any advice?
Thanks

Well, doesnt look like a sleep problem after all, as I've disconnected all HDs and still no BIOS, no display at all.
Computer isnt turning off repeatedly, only once about 3 seconds after turning on, so its not overheating.
Could my video card have randomly died...?
Strange timing...
Any ideas anyone?

Wait... you start it up and then it shuts down after 3 seconds?? Ugh... I have this issue with my C2D in storage atm... will be interressed in a solution.

Do you get any beep codes from the motherboard?

http://www.computerhope.com/beep.htm

Regards....Mike Connor

Nah, no beep codes, that would be too simple right?
Well, I stripped it down completely just to check. Barebones PSU and mobo only. Still turned on for three seconds, off, then on again. Obviously its not as the result of any expansion card or HD. There's no way that the processor is overheating and there are no beep codes, so I'm completely stumped.
Only other possibility is a bad PSU I guess, but its been working fine for three years...and why now?
Mobo: ASUS P5Q Premium
CPU: Core2Duo E6850 3.00GHz
PSU: OCZ GameXStream 700w

So me too, no beep codes (Phoenix BiOS; Gigabyte P35-DS3R). That's what I thought... the PSU is doing some bad short circuits himself; thus stopping when it happens. Except mine is an Antec 500W.

In that case either the motherboard or the power supply has a fault. It does happen. Sometimes a failing power supply can also kill a motherboard, Depends on how and why it failed. If you are lucky it is only the power supply. Seems most likely.

Easiest way to check is to try a new power supply.

Obviously you never get to the POST ( Power On Self Test) so you don't get any beep codes.

Do let us know how you get on. I am off to bed now, I am really too tired to do any useful work.

Good luck with your troubleshooting.

Regards....Mike Connor

Check CPU temperature, I had similar problem some time ago, upgraded Cooler.

Finally got new PSU in. Did nothing to solve the problem. Only thing left could be a mobo short (unlikely since its less than a month old and I haven't had any problems with it yet) or CPU overheating/not seated correctly. This doesnt seem to make sense either since I havent had any trouble with that either...
Doesn't make sense at all...

err - just pull the electrics/plug from wall socket for two minutes. (no electric connection) pull battery on a laptop!

If it still won't start - pull all usb etc leads out then just plug mouse/keyboard in and you should be good to go!