Symptom
After updating to Mac OS X 10.2.5 and waking the computer from sleep, the image on the built-in or external display appears garbled.
Solution
To avoid this issue, set the Displays preferences to the native resolution for your display. The native display resolution the PowerBook G4 (17-inch) and iMac (17-inch 1GHz) computers is 1440x900.
The native resolution for LCD displays connected to a Power Mac G4 vary depending on the model of the display. Typically, the native resolution is the highest resolution available in the Displays preference pane.
If you did not take this precaution before installing the Mac OS X 10.2.5 Update and you see garbled video after waking the computer from sleep, follow
these steps:
1. Restart the computer.
Important: If you cannot see on-screen video to do this, press the keyboard power key, then press the Return key. After the computer shuts down, start up again.
2. Choose Apple menu > System Preferences.
3. Choose View > Displays.
4. Select a different resolution.
5. Choose Apple menu > Restart, and click Restart.
6. After the computer restarts, you can switch back to the original resolution and the symptom will not recur.
Note: As an alternative to steps 2-5, you may reset PRAM by pressing the Command-Option-P-R keys combination as the computer starts up, until you hear a second startup chime. This restores certain system settings to their default values. For more information, see technical document 86194: "Mac OS X: What Is Stored in PRAM?".