This cold be due to a BIOS setting - designed for incoming faxes and other remote access. You will need to go into the BIOS to fix it>

Usual way to the BIOS is by restarting your computer and pressing the Delete key repeatedly as it starts to boot up, until you enter the BIOS  Screen.

1. Once in BIOS, go to Power Options.

2. Use the arrow keys to move down to Wake On LAN and/or Wake On Ring and change them to Disable  (usually done with the page up/down buttons).

This will prevent the computer from being able to come out of its power down mode whenever the phone rings or if LAN activity occurs (ie: you have another computer in the house on a network and someone logs on to the network from there).

Press F10 and choose YES to save settings and exit.