In your computer's BIOS {please check your owners manual on how to change}
there are settings for power management. One of the settings is to allow
the computer to be woke up or powered up by and depending on your
motherboard and manufacturer, from lan, modem, keyboard, serial port, mouse,
usb. One of those has been set to wake on serial or wake on modem. That
way when your phone rings your computer thinks its is suppose to wake up and
turn it self on. Neat feature if you need to use, but can be annoying if
you want your computer to stay off.
