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A couple of days ago I came back from a meeting to find my laptop had locked up. Power lights still on but the screen was blank (by which I mean black, though still "backlit" so not dead). Didn't respond to anything.

I rebooted and it powered up fine and I got to the login screen. I logged in and it seemed to be going fine for about 30 seconds (gmail notifier and pidgin popped up) then the same thing happened - black screen.

If I boot into Safe Mode it's all fine, no problems.

A virus is possible but seems very unlikely - it's a work laptop so is never used for anything dodgy and it's running a firewall and continually updated AV software. My gut feel is that this isn't malware and a Malwarebytes scan shows nothing.

I've tried removing everything from the startup folders (All users and my login), everything from the Run section of the registry (Local Machine and my login) and I've disabled every service which doesn't run in Safe Mode (assuming anything running in safe mode is OK) but the problem still exists.

I've scanned the memory for errors (all fine).

Any thoughts on what else I could try? Not necessarily looking for a solution, just suggested next steps.

EDIT: Resolution - so, no idea why at the moment but it turns out that the service causing the problem (or at least the one where if you disable it it the problem goes away) is the Power service. For now I can live without this so just disabling it until I have more time.

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up vote 4 down vote accepted

Your first port of call is to log into Safe Mode and check the Event Viewer to see if it is reporting anything pertinent.

Secondly, rather than removing all your start-up programs and hacking into the registry, you could have used msconfig to restrict which applications and services are started with Windows - I'd give it a try; you might want to temporarily disable some non-essential services.

The blank screen could be caused by lots of things but uninstalling your display adapter (via Device Manager) should make the PC boot with a generic driver - you can then download and reinstall the latest version of the appropriate driver.

As a priority though, I'd log into Safe Mode, or better still, boot from a Linux Live CD - and backup all your important files, such that you can restore them if the situation proves fatal and you need to rebuild.

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+1 for msconfig tip which is a MUCH nicer way of playing with services. Turns out it's the power service causing the problem. No idea why but happy to have it resolved and actually get on with some work. Big tick for you sir... – Jon Hopkins Apr 15 '10 at 12:41

Could be a hardware defect. Since Windows loads the "bigger" drivers in "normal" mode, it sometimes causes defective sections of hardware to be loaded. Or you have a piece of hardware which is not touched at all in safe mode (unimportant things like TV cards?)

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