Macbook keeps waking up when lid is closed

[XtraKrispi]

Hi, my Macbook (intel core duo) keeps waking up from sleep mode when the lid is closed. I have read that Bluetooth or an external device (such as a mouse) may cause it to keep waking up, but I have turned off Bluetooth, and I do not have a device attached to the computer.

Does anyone have any suggestions as to what the problem might be, and how to fix it?

Thanks