The mouse does not function if you start up an iMac computer with a tray-loading CD-ROM drive using the Apple Hardware Test (iBook) 1.1 CD, and you can't choose to restart or shut down.
Solution
Press Shift-R to restart or Shift-S to shut down.
Note: Apple Hardware Test (iBook) 1.1 only works with the Apple iBook (FireWire) computer.