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Hi I am running a (until yesterday) stable PC with Vista.

Since yesterday, I've had four instances of this problem:

The system, without warning, completely stops responding - no reaction to mouse or keyboard (including Ctrl-Alt-Del). Screen just freezes. Only reset button works.

As far as i can tell, I'm not doing anything unusual, it's not the same software running each time (firefox, outlook, VS 2008, etc).

Any ideas where I should start looking to diagnose this? Could it be RAM? Software / OS? CPU even?

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Is your system still under warranty? A system that freezes could be any on the list you gave (including drivers). Have you made any changes to your system recently? Now might be the time to roll back any installs.

The most effective way you can debug this is to strip the motherboard down the the bare essentials (motherboard, CPU, power supply, 1 stick of memory, video), do a clean install and add things back to the system one at a time until you can reproduce the failure. Then test various configurations around the failing component until you can find a working configuration or remove the failing component (assuming it isn't the motherboard). Also swap out the processor, PSU, memory with known good parts.

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Take a look at see if anything stands out in: Control > Admin Tools > View Event Logs or %windir%\system32\eventvwr.msc

I'm not too familiar with event viewer, but seems like a good place to check and will have logs of system and hardware problems.

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up vote 1 down vote accepted

Turns out it was heat - my power supply fan had died, and I hadn't noticed.

A new fan fixed the problem.

Thanks everyone.

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