My computer is only a few months old, but about a month ago the computer started to turn itself on. This happens sometimes straight after turning it off, or sometimes hours later. So, I have been turning the computer off at the wall. The computer is a Pentium 4 running Windows XP Professional.

Some computer BIOS have the option to wake the computer on certain events, such as ‘Wake on LAN’ which will start the machine remotely after being sent a ‘magic packet’. Other settings can include ‘Wake on ring/modem’ to start a machine when the phone-line rings, and ‘Wake on alarm’ or ‘RTC alarm wake up’ which will start the machine at a specific time. It is possible that kind of option is enabled and causing the problem. We will need to explore the BIOS to check these settings. Just be aware that this is a delicate area of the computer so don’t change any settings if you are unsure about their function! Restart the computer and enter the BIOS setup. You usually have to press a specific key to trigger the BIOS setup (during the power on self test you should see a message like ‘Press F1 to enter setup’). Once you are in the BIOS setup, go to the power management section. Look for any wake settings (there could be others in addition to the ones I listed above). Make sure they are not being used to start the computer.