My new laptop, a Dell Studio 1535, has started exhibiting a strange problem as of late; when I hibernate it over night, it resumes early in the morning, waking me up with the fan spinning.

I was preparing to send the thing back to Dell, when it happened one night and I checked out the event logs. It turns out that Windows Update was resuming the machine from hibernate - and then updating itself. After turning this off, I've had a good night's sleep! Also, Windows Defender was scheduled to scan the machine every morning at 2.00am, so that's been disabled too.

I hope this post can provide answers to anyone else experiencing a similar issue.