Windows 7: System Hung followed by No Display

It just happened today subsequent to the following snag:
While working I marked that there is no sound, and this have happened before too,
so in the sound property the Firewire device was missing. It is and was my default device. I uninstalled and reinstalled, luckily Maudio now have, atleast in the list of OS, a driver for Window 7 x64.
After a few hitches the sound restored and all went well for about two hours.
And then suddenly the mouse went dead, no response by cursor i.e. no movement. Contr-Alt-Delete no response.
Had to force shut down. On starting again there was no response seen on the monitors, the orange light did not go blue as usual, and the power on the pc after some seconds went off, came on and off and the cycle continued. Again forced shut. Then completely shut down and after 20 seconds started but the same behavior.
Last time, when this machine was made the same problem on the same motherboard model was noticed and the MB was replaced by Intel.
Just unable to understand, nor can I go in the safe mode, nothing.
Had been smoothly working since then and now this!
Please give me some guidance on this. Have sent a mail to Intel support on this just a few moments before.
Thanks