Apple PowerBook (2400c) - Manual (Page 24)

Trouble? If a problem with the computer prevents you from using the Power
key or choosing Restart—for example, if the computer “freezes” so that the
pointer does not respond to the trackpad—you can restart the computer by
pressing the Command (x), Control, and Power keys simultaneously.
If the computer doesn’t restart, press the reset button (marked with I) on the
back of the computer.
(If the computer is on but “frozen,” pressing the reset button will turn off the
computer. You will then need to press the Power key to turn it on.) Use this
method only if you cannot choose Shut Down or Restart from the dialog box
that appears when you press the Power key, or if you cannot choose either
command from the Special menu.
I Reset button
23 Getting Started