I have this problem where my laptop, seemingly randomly, turns itself on (from hibernation). This is very annoying as it usually does it at night, draining the battery.

It does not seem to be anything in the BIOS, any ideas?

Might be a service that is allowed to wake the computer from hibernation. Typical cause would be wireless networking service kicking in for some reason.

Hmm, wi-fi is usually disabled, I'll have a look through the services, though.

After some more observation, it seems to do it every day at exactly midnight, meaning it must be a timed thing. Any ideas?

It's a were-computer, contact me privately as I know people that specialise in this sort of thing...

Some media applications make use of the fact that a computer can turn itself on to do stuff. Like WMC optimisation etc. check such applications also look in scheduled tasks

Sounds possessed. Get it exorcised. Immediately.

turn off the fan ^^