Apple Macintosh PowerBook 190 Series - Manual (Page 94)

The computer displays a flashing question mark icon.
m This icon usually means that the computer can’t find system software
on any disks attached to the computer. (After it displays this icon for two
minutes, the computer will shut itself off.)
If the computer is connected to any external hard disks, make sure that the
SCSI chain is terminated properly (see “Connecting SCSI Devices” in
Chapter 4) and that the external hard disks are turned on. Then restart the
computer. If the problem recurs, the hard disk or its system software may
be damaged. See Chapter 8, “Diagnostic Techniques.”
m Turn off the computer, disconnect all external devices except the power
adapter, and restart the computer. If the computer starts up, turn to
“Problems with Equipment Connected to Your Macintosh PowerBook,”
later in this chapter.
The computer freezes or displays an error message during startup.
m Turn off the computer, disconnect all external devices except the power
adapter, and restart the computer. If the computer starts up, turn to
“Problems with Equipment Connected to Your Macintosh PowerBook,”
later in this chapter.
m Start the computer, holding down the Shift key until you see the message
“Extensions off” in the Welcome to Macintosh box. If the computer starts
up, turn to “Checking Your System Software Extensions” in Chapter 8.
About the codes in error messages: The number codes in error messages are
used in software development. Sometimes they can help a technician narrow
down the source of a problem. However, the codes are usually too general or
technical in nature to help you diagnose a problem yourself.
87 Tips and Troubleshooting