Serious problem - no boot, no bios, no nothing

I really hope someone can help.
I installed windows 7 as an upgrade - everything seemed to be working ok for a few days at least.
Went to bed one night, got up next morning and no computer functionality although the computer power light was on.
I couldn't even power the computer down using the power button.
I unplugged the computer and then reconnected, the power light came on, the fan started, the dvd drive whirred briefly, the disc drive light came on briefly and then nothing else - no bios prompt, no Packard Bell splashscreen, no screen activity at all, no nothing but I can open the dvd tray.
So based on some of the responses on the forum I put the Windows 7 upgrade disk into the dvd tray and powered the computer down then powered up again. The power light came on, the fan started, the dvd whiired quite a bit this time, while it was whirring the hard drive light came on briefly, then the dvd drive stopped and then nothing - no bios prompt, no Packard Bell splashscreen, no screen activity at all, no nothing.
Normally I would have suspected a hardware fault - especially if I'm not even getting a bios prompt but I just wonder whether there's anything else as I recently upgraded to Windows 7.
Please if there is anyone out there who might be able to shed some light on this I am getting really desperate and worried.
Thanks if you can help,
Trevor

Sorry - I cant help you myself but it happned to a friend of mines laptop when he installed the rc1 version. He had to buy a new laptop.

If you aren't getting the chance to get into bios, then you have a hardware issue. Does your computer make any beeps, or does the motherboard have a digital read out for error codes? If so, please relay what the beep pattern or error code is.

Try swapping out video cards. If you're using onboard video, try plugging in a PCI-E(or AGP/PCI... but hopefully your computer isn't that old). If you're already using a 3rd party card, unplug it and either use onboard video, or if that isn't available try a different video card. (This is all assuming you're a geek like many of us that have whole or parts of machines around that we can use for parts).

If not, then start unplugging things. First all of the hard drives and DVD drives. Boot it up and see if you can get to bios.

If that fails, pull out all but one of the sticks of RAM (leave one in the slot closest to your CPU or bank1) and boot it up and see if you get anymore response from the board. Try two different sticks of RAM in the one slot (one at a time obviously).

If that doesn't get you anything, pull all of the RAM out and boot it up. If you still get nothing, no beeps, nothing on the screen, then you're likely SOL. You probably need a new motherboard and/or a new Power Supply(PSU). If you want to keep as much as possible, you should check your PSU with a Power supply checker, and test your motherboard with a different (known to be working) power supply.

On restart, keep tapping all fingers on the ff3 to F9 key and keep tapping until a screen pops up,

No guarantees, but it;s worth a try