I bought this laptop in England new for around $2,200, it sold with a one year UK warranty.
It was a pleasure to use during the first year.
One week after the warranty expired it crashed during a sceduled Norton virus scan. A hard reset was needed to get it working again, it booted partially, then froze again. Another hard reset, and the Vaio then just sat there dead. The only sign is a constantly lit green num-lock LED.
Pressing the power button yields nothing: no beep, no hard drive activity, no flashing lights.
The power supply has been checked and is ok, the battery is ok, as is the hard drive.
I have tried the reset button with and without a battery, removing the cmos battery for a week, removing and exchanging the ram.
Of course Sony refused to honor the warranty as it was 1 week over, and wanted to replace the motherboard for a ridiculous amount of money.
It has now been sitting on a shelf acting as a paperweght for the last 2 years, and the num-lock LED is still lit steadily when hooked up to the power supply.
I refuse to believe that an expensive, hardly used Sony product can die this way.
If anyone has any advice on what could be the fault, and if it can be repaired for a reasonable sum I would be grateful.

Most likely it is a well known problem with Sony motherboards - contacts in RAM slots are loose and need to be resoldered. Try to open the memory cover, if there are two memory sticks there remove one of them and try to turn computer on. If that won't help than try another slot. 90% that one of them would work. Post your results here please.

Thanks for the response.
I think if it were a RAM issue, there would be some response from the computer on pressing the power button. In my case the computer is completely dead, no beep, no hard drive activity, no flashing lights.
The only indication that the laptop is hooked-up to a power source is the constantly lit number-lock LED.
I have already tried removing and replacing the RAM, but it is still completely dead.
Does anyone knows the meaning of an illuminated num-lock LED in an otherwise dead Vaio?

I had several Sony laptops that did not respond to the power button - resoldering the contacts on the RAM slots helped. But these laptops had three lights lit when power button was pressed... Blinking of one led shows that Sony internal protection is enabled and it blocks powering up the laptop until the problem is solved. I told you what is most probable but may be something else... It's hard to say something without having it in front of me..