Laptop waking from sleep

I have a laptop which has "recently" turned into the proverbial baby, and refuses to sleep through the night, or for that matter, through some days. I'm a little lost when it comes to trying to debug what is causing it to wake for no apparent reason.

EDIT:

Powercfg tells me:

C:\>powercfg -lastwake
Wake History Count - 1
Wake History [0]
  Wake Source Count - 1
  Wake Source [0]
    Type: Fixed Feature
    Timer Expired (RTC)

So it appears something is set an alert to wake the system up? But how would I find out what?

Solution 1:

You can use the PowerCfg utility to find out. It's part of Vista, no need to download it.

powercfg -lastwake

Will tell you what woke up your laptop.

To see all devices that can wake your computer, try:

powercfg -devicequery wake_armed

You can turn all these devices off with Device Manager, on the Power Management tab. Unselect "Allow this device to wake up the computer".

Solution 2:

Tracked it down to be Windows Media Centre downloading the TV guide every four hours or so -- disabling that now lets the poor laptop sleep for as long as it likes.

Solution 3:

Things to check:

• Scheduled Tasks
• Backup Jobs - (For example Windows Home server for home Other backup solutions for business)
• Automatic Updates set at default (3am)