Apple iMac (21.5-inch and 27-inch, Mid 2011) - Manual (Page 48)

48 Chapter 4 Problem, Meet Solution
If the problem reoccurs when you use a particular application, check with the
application’s manufacturer to see if the application is compatible with your iMac.
For information about the software that came with your iMac, go to
www.apple.com/downloads.
If the problem occurs frequently, try repairing your disk, restoring your software from a
backup, or reinstalling your system software using the Mac OS X Utilities pane
(see “Repairing, Restoring, or Reinstalling Mac OS X Software” on page 50).
If your iMac freezes during startup or you see a flashing question mark
 Wait a few seconds. If your iMac doesn’t start up after a delay, shut down your iMac
by pressing and holding the power button (®) for about 5 seconds, until it shuts
down. Then hold down the Option key and press the power button (®) again to start
up your iMac. Keep holding down the Option key until your iMac starts up, then click
the arrow under the icon of the startup disk you want to use.
After your iMac starts up, open System Preferences and click Startup Disk. Select a
local Mac OS X System folder.
 If the problem occurs frequently, you may need to reinstall your system software
(see “Repairing, Restoring, or Reinstalling Mac OS X Software” on page 50).