Windows 7 gave my PC insomnia

I’ve never really liked Windows Vista – it had too many annoying habits and not enough good ones for me to bother with it. However, I was always envious of its Sleep mode – Hibernate in XP is fine, but Vista's Sleep is much better. I was therefore keen to use Sleep after installing the Windows 7 RC, but there was a problem.
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I could put my PC to sleep, but after a short period – sometimes just minutes, sometimes up to an hour – my PC would wake up again. Unfortunately my PC is in my bedroom, isn’t particularly quiet, and has far too many blue-LED fans in it. Imagine my response when I was awakened by weird-looking light show and loud whirring sounds at 1am. The bedsheets remained dry, but it was a close call in my confused and groggy state.

The odd thing was, the PC wasn’t doing anything. It wasn’t downloading a fake update, or starting a virus scan, or running some other scheduled event; nothing was happening, it had just woken up.

Windows 7 has given my PC insomnia.

Some hunting on the interwebs turned up this article on Sleep issues with Windows 7. It seems that Windows 7 has some odd network controller behaviour by default – even when the PC is in a power-down state, the network controller feels it needs to poll the network to update its status. Why, I have no idea; the PC’s off, so it has no need to update anything until the power comes back.

Anyway, the way to fix this is to enter Device Manager, right-click on your network controller(s),click Properties and go to the Power Management tab. Then de-select the option "Allow this device to wake the computer." It says on the forum post I’ve linked to that this is a problem with XP and Vista, but none of the Vista or XP PCs I’ve checked give the network controller the power to wake the PC by default, so it does like a Windows 7 quirk.

As the post says, opening the command prompt and entering powercfg -devicequery wake_armed does give you a readout of every device that has the Power of Insomnia, so you can hunt out other devices causing Sleep issues if the network controller wasn’t to blame. Happily, I can now use Sleep mode, though I’m not sure that this is the full reason for why I woke up so early this morning that I was in the office 20 minutes early.