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I have a Sony laptop, and it sometimes passes the bios screen, it sometimes passes the Windows login screen and after it reaches Windows 7 64bit. It works fine for like half an hour, until it would randomly freeze (nothing blinks, nothing happens, keyboard unfunctional). I have to hard reset the laptop by taking out the battery. Looking at the windows event log, it's telling me that I've had a critical Kernel-Power error causing the computer to crash.

After it crashes, and I hard reset the laptop it becomes hard to turn on again, after I press the power button, the green power indicator will turn on for a moment and nothing else will happen.

I have to wait a while, maybe 15 minutes to properly turn it on again. With the luck of it not hanging at any of the boot screens, I will see Windows again.

I've tried taking out the ram, battery and hard drive, yet it doesn't effect the power button not being able to put the machine into boot sequence.

I've ran Windows memory diagnostics on the ram and it told me it was fine.

I just want to know where the problem might lie in your experience.

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Can you upload error log. – avirk Aug 11 '11 at 17:00
I'll do it as soon as I'm in windows again : ) – Mohammad Aug 11 '11 at 17:05
up vote 1 down vote accepted

Remember you need to run the memory tester for at least 24h to be reasonably certain that memories are OK. 3 days is recommended, and even then you can't been 100% sure.

If that does not help, another source of strange crashes is power delivery circuitry which feeds power from battery to the CPU and other components. If it's about to fail, the voltages can sag every now and then causing OS to crash. In case of laptops there's really not much you can do to that except possibly swap the whole motherboard.

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Does this also explain why the laptop will refuse to turn on after a hard reset? Thank you! – Mohammad Aug 11 '11 at 16:48
Machine needing hard reset just means it's totally crashed. It's hard to say why, but it just means even low-level routines of OS are non-responsive. Either bad memory or bad power circuitry can cause this, but if I had to guess, I'd guess the power. – Zds Aug 11 '11 at 17:02
Quite true. I once let it stay frozen in the Windows environment and it rebooted itself after a few minutes. – Mohammad Aug 11 '11 at 17:06

It could be also a thermal problem. Check the CPU core temp and verify if all the coolers are working.

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