Issue: Screen Saver freezes computer

Several users have described an issue where, upon activating the screensaver, the computer crashes.

Apple Discussions poster alamosakid writes:

"Whenever I turn my screensaver on, my MacBook freezes. My screensaver is set to mosaic pictures, I think. When I drag my mouse to the lower right corner, the screensaver doesn't start and all I can see is the time (if the time ever shows up). Then I shake my mouse, etc, to try to get back to my desktop and my computer freezes and I have to restart it."

This problem may occur with third-party screensavers, but also has happened with some of the built-in screensavers that deal with the iPhoto library. Problems can include a full system crash, or a System Preference crash, but, most often, the system will hang with the screensaver starting up. For instance, with the photo gallery screensaver, users might just get a black screen with the text "Searching for photos" in the center.

The fixes for this issue include reinstallation the affected screensaver, or in the case of built-in screensavers, tackling potential problems with the iPhoto libraries that might be causing the hangups. However, while the specific problems might be anything, users can regain control of their computers with the following suggestions:

Fixes and Workarounds

Use the terminal to kill the screensaver When the screen is frozen or is hanging with the screensaver activated, users may not be able to interact with their machines through the keyboard, even with a force-quit key sequence (opt-cmd-exc). Using screen sharing will only show the same screen on the remote computer as well, so the only way to regain control is to kill the screensaver using the terminal.

To do this, with a second computer on the local network, open the terminal and enter the following:

ssh username@COMPUTER

In this command "username" is the name of the administrator account on the affected computer, and "COMPUTER" is the name of the computer (ie: Johnnys-Laptop). Alternatively, it could be the IP address of the affected computer.

NOTE: This requires the computer to have "Remote Login" enabled in the sharing preferences.

After logging in, enter the command "top" to display the running processes on the computer. Search in the list for the "Screen Saver" application, and note the number to the left of it (should be a four-digit number). Press "Q" to quit "top", and then enter "sudo kill number", where "number" is the four-digit number noted earlier.

Upon pressing enter the screensaver should exit and reveal the desktop again. From here, it is recommended that users change the screensaver to prevent any further hang-ups.

Manually edit the screensaver preferences For users where the screensaver preference pane causes crashes, editing the screensaver preferences manually may be the only option. To do this, go to the /username/Library/Preferences/ByHost/ directory and open the com.apple.screensaver.(number).plist file in a text editor. From here users can do the following:

Set the screensaver activation time to infinity Under the "idleTime" key, set the integer to "0" and save the file.

Change the screensaver to a built-in one In the "moduleName" key, change the name to "Flurry", and in the "modulePath" key, change the path to /System/Library/Screen Savers/Flurry.saver. Alternate names can be used from the files in the /System/Library/Screen Savers/ folder.

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