Apple PowerBook (3400 series) - Manual (Page 121)

This chapter provides a step-by-step approach to diagnosing and solving
problems involving system software and hard disks. Try the steps listed in
each section in the order they are given until your problems are fixed.
Checking your system software extensions
System software extensions are files that add features to your system software.
Some extensions are incompatible with one another or with certain programs.
To check whether an extension is causing problems, follow these steps:
1 Start up the Macintosh PowerBook while holding down the Shift key. Keep it held down
until you see the message “Extensions off” in the Welcome to Macintosh box.
This procedure turns off extensions.
If this procedure solves your problem, then continue with this section. If not,
then turn to the next section, “Testing Your Hard Disk.”
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8
Diagnostic Techniques
Consult this chapter before you
call the Apple Assistance Center
to solve problems with system
software and your hard disk.