This is from an earlier post by Rick Rogers. You have to be fairly brave to
change the BIOS. This also raises the question of how this got changed in
the first place...
"You likely have a "wake on..." setting enabled in the system BIOS. You must
go into the BIOS to correct it. It might be "wake on ring" (starts when the
phone rings if a modem is connected) or "wake on lan" (starts when it is
pinged from a broadband network connection).
To enter the system BIOS, click start/shutdown/restart windows if you are
currently running, or simply start the system.
After windows shuts down, the machine begins to reload. At this point you
should either have a manufacturer logo screen or a POST screen that shows
the hard drives and other devices being detected. You need to enter BIOS at
this point before windows begins to load.
If it is the latter, there should be a line that says "Press <some key> to
enter setup", you will need to depress the indicated key.
If you get a manufacturer logo, you can try referring to the manual you
received with the pc to discover which key you need to depress while the
logo is being displayed or you can try hitting the escape key. Generally,
the keys used to enter the BIOS are F1, F2, F10, <delete>, <escape>, and the
space bar, though there are some others.
Once you have made your changes, you want to "exit saving changes", usually
F10, to restart the system."
