Leopard has started booting my iMac on it's own!

I was using the System Preference -> Energy Saver -> Schedule options on my iMac to shcedule the machine to shut down each evening and boot each morning.

I recently turned these off, but now my machine has decided to boot each morning at 1am. As it's currently in my bedroom this is really annoying!

I wonder if anyone knows how to stop this - the only solution I've found is to unplug the power cable which is far from ideal.

Where are the settings stored, and can they be reset from somewhere else besides the energy saving schedule panel?

Thanks