M4400 "A possible processor failure has occurred"

My M4400 has developed a nasty bug over the last two days.
This has happened about 6 or 7 times so far:

Laptop functions normally for a couple hours under either Windows or Linux.
Laptop is placed into sleep by closing the lid.
A short while later, the laptop is opened and has a constant power light, no display and no backlight on keyboard - no response to any input.
Laptop is hard reset by holding the power button.
Laptop refuses to start - repeated attempts to turn it on eventually get it to display error code (num lock flashing, others solid) - "possible processor failure".
30 min of waiting later, laptop boots fine and functions perfectly for hours until the cycle repeats.


I have already contacted Dell Workstation Support via email, and am currently going through the usual motions. The woman at the other end clearly has never encountered this issue before, and is making logical but irrelevant suggestions for troubleshooting. I ran the BIOS level diagnostics - no failures found.

Does anyone have any idea what this could be, and what I should ask to be replaced? Get a replacement unit even? Mine is pretty scuffed up, don't think they'll be too happy about that. It's well within the 3 year next business day service warranty though.

 

try to check if it is overheating

 

Have you tried a known good socket P processor?

 

Well, I got a logic board replacement now. We'll see if the issue has gone away.

No, it wasn't overheating, and the processor is fine under heavy usage when it does boot.