Apple System 7.1 - Manual (Page 6)

Cause: You probably have an incompatible item in the System Folder.
Solution: You need to start up the computer and remove any incompatible items from the
System Folder.
When you turn on the computer, press the Shift key and hold it down until you see the
"Welcome to Macintosh" screen. Holding down the Shift key while the computer is starting
up causes the computer to ignore any special startup programs (extensions) in the System
Folder.
If holding down the Shift key doesn't work, you can start up the computer using the Disk
Tools disk included in your upgrade kit.
Remove potentially incompatible items from the Extensions folder and the Control Panels
folder (inside the System Folder), and restart your computer.
You Can't Print
Problem: When you try to print, you see a message that the printer could not be found.
Cause: You need to select a printer.
Solution: Use the Chooser to select a printer. (For instructions on how to use the
Chooser, see the Macintosh User's Guide.)