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I have a windows 7 x64 machine which sometimes (not all the time - no discernable pattern) when I tell it to sleep turns off the monitor but never powers off the machine (left it overnight). It then won't wake up, tried the keyboard, mouse and power button.


to be clear the machine turns the screen off like it is going to sleep, but then the fans/disks/cpu do not turn off and the power light on the front of the machine stays on. Once it is in this state it can then be 'woken'


My only option seems to be to hard shut off and reboot.

Why might this be?

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Have you tried updating your drivers? There is probably something preventing it from successfully turning off all devices, the system thus hangs while trying to get to sleep. – Tom Wijsman Aug 12 '10 at 12:03
I would agree with @TomWij - an application perhaps? When in sleep you would need to hit the power button to waken it, AFAIK keyboard and mouse would never wake from sleep? – w3dk Aug 12 '10 at 12:09
if you set in the bios that USB devices can wake from sleep then yes, USB mouse and keyboard can wake the machine, assuming it has gone to sleep correctly. – Sam Holder Aug 12 '10 at 12:37
up vote 4 down vote accepted

The Windows Reliability Monitor can often give you reasons for sleep/hibernation failures in Vista and Windows 7. It showed me in the past that the driver for a piece of USB hardware I had was breaking sleep, once I uninstalled that I had no problems.

Click on the Start button and type reliability and it should show up in the listings, start that and then after it spends a few seconds scanning, it should show you a time-line with significant events including Application Failures, Windows Failures, etc.

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this sounds like just the thing I was looking for, I'll check it out. Thanks. – Sam Holder Aug 12 '10 at 12:38

I'm not sure about it not waking up anymore, but for the machine to power down you need to put it into hibernation mode, sleeping won't power down the machine completely.

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sleep powers it down so that the CPU, hard drives, fans etc are all turned off, just enough energy is used to keep the system status in ram. whilst what you said is factually true in effect sleep is 'powered down' to most people. For me sometimes the machine doesn't turn off the fans/cpu/hard drives etc when it sleeps. – Sam Holder Aug 12 '10 at 10:57

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