Apple Mac Pro (Mid 2010) - Manual (Page 95)

95 Chapter 4 Problem, Meet Solution
If the screen freezes
 Force the frozen application to quit. Hold down the Command (x ) and Option keys
and press Esc. Then select the application in the list and click Force Quit.
 If that doesn’t work, force the computer to restart by holding down the power button
(®) for 5 or 6 seconds until your Mac Pro shuts down. Press the power button (®)
again to start up your Mac Pro.
If your display has a light on the front and it’s flashing
On some Apple flat panel displays, the power light displays a series of short flashes
when an error is detected.
 If you see a repeating sequence of three short flashes, the display is detecting input in
the wrong video format. Make sure your display is compatible with your graphics
card and that you’ve installed the correct display software, if your display came with
installation software.
 If you see a sequence of two short flashes and a long flash, the display is detecting a
problem with a backlighting lamp. Contact an Apple Authorized Reseller or Apple
Authorized Service Provider.
Problems with Your Internet Connection
If you have trouble with your Internet connection, you can try the steps in this section
starting with Network Diagnostics.
To use Network Diagnostics:
1 Choose Apple () > System Preferences.
2 Click Network and then click “Assist me” at the bottom of the page.