Mysterious Laptop Problem - Powers Off Suddenly / Doesn't Turn On

A couple of days ago, my laptop started powering off suddenly. One second it's on, and the next, no hard drive activity, no screen, no nothing. This happens in an instant and without warning (no blue screen). Starting yesterday, the problem got worse. After the power cut out, I would have trouble starting the computer up again. Sometimes it worked, sometimes it didn't. When it did work, I sometimes got as far as the Windows login screen. When I hit a key to begin typing my password (or swiped my finger on the fingerprint scanner), the power cut out. Today, it seems to have gotten even worse. Sometimes the startup process doesn't even get as far as the Windows login. A couple of times today, I pushed Power, got the the Windows Startup Error screen, selected to resume Windows as normal, and bam! Power's off.

Now, this gets even more mysterious. Sometimes I push the power button (after one of these instances), and nothing happens. Sometimes I push the power button, and the power light comes on, and then the fan, but no hard drive activity. Dead. Sometimes the computer won't start up at all unless I remove the battery, pull the plug, wait a few seconds, and then try again.

Even stranger... I have the computer on right now. It's been on for 5 hours, and it's working fine. I'm afraid to turn it off or put it to sleep, because I know it might not start up again.

If you are thinking overheating is the source of the problem, as of right now, after being on for 5 hours, each of my two processors is running at 53 deg. C and 45 deg. C, which I don't think is very hot.

I've been using computers for 25 years, and I've never seen anything like this. Any and all advice would be greatly appreciated. Thank you!

Specs:
Sony Vaio VGN-Z90US CTO: Core 2 Duo P9600 (2.8 GHz), 4 GB DDR2, 200 GB 7200 RPM HDD, 256 MB nVidia 9300M GS GPU, 13.1" 1600x900, Windows 7 Ultimate

 

First off, backup all important files using a flash drive or similar.

It's as if something like a cable powering the machine inside is loose. This has the possibility of making the original problem even worse, but have you tried, quite literally mind you, shaking the Z? Any loose-ish sounds? (keep in mind the port replicator cover should be held or taped down as that's loose in itself).

Looking at the specs, you've got the 1st gen VGN-Z, a Japanese machine. And you've stated a 200GB HDD. From memory, the VGN-Z Japanese CTO came with a 250GB HDD as its smallest customized option. Which tells me you've switched out the HDD in the past? Or is that a typo for a 500GB HDD (which is the highest HDD you can get before the SSDs kick in).

Before the issue became chronic, have you noticed something noticably different on your Z? Random sounds, unusual heat, unexpected freezes / lags? If you heard sounds,
http://forum.notebookreview.com/6681203-post22.html

Was it similar?

Regardless of the issue, it might require you do open your Z up and make sure the thing is intact internally (wires, connectors etc etc). And provided your machine wasn't 'roughed up' in the past with strong dings and bangs and drops, I think your VGN-Z is 'saveable'.

 

Is the notebook hot when it turns off?

As you can see I've got the same Z gen as you. My motherboard and fan already got exchanged after my unsuccessful attempt to repair this problem by myself. Sometimes the fan basically doesn't kick on...

Are you running your notebook in Silent mode? My problem was partially solved by changing the mode to balanced...

 

i have better suggestion...

try running the notebook in safe mode see whether it will shutdown by itself...

 

Is your notebook plugged in or running on battery when this happens? If it only happens on battery your battery may need to be replaced. May want to try running it plugged in with the battery removed.

I have seen almost the exact same thing happen on a couple of desktop machines that were extremely dusty inside. Opening up and cleaning them stopped this occurrence.

Could be a transistor failing when it gets warm.

 

Is your fan spinning? is the port by the fan extremely hot? Can you actually feel airflow coming out of the vent?
If the laptop is overheating and shutting down due to thermals it wouldn't turn back on until it was under the thermal threshold again.