How to Troubleshoot a Blue Screen on a Mac

by Mario Calhoun

If you have the Application Enhancer plug-in installed on your Macintosh computer, you may experience conflicts between the plug-in and your Mac's Leopard operating system that can cause operational issues. Any changes to the operating system's firmware can render a previously compatible application plug-in useless, or result in a blue screen error. In order to fix the error you must remove the plug-in from your computer, or avoid using the application until you install an updated version of the Application Enhancer compatible with your Macintosh Leopard operating system (see Resources for link).

Repair using Terminal


Press and hold the Power button on your Mac until it shuts off, releasing the button when it does.


Press the Power button to restart the computer, then hold down the "Command" and "S" keys simultaneously, until your computer boots in Terminal mode. In Terminal mode, your screen will have a black background with white lettering. The letters and numbers are commands for your computer. While in this mode, you are allowed to enter commands to remove the software from your operating system.


Type "/sbin/fsck -fy" and press the "Return" key on your keyboard. Type "/sbin/mount -uw /" followed by pressing the "Return" key and typing "rm -rf /System/Library/SystemConfiguration/ApplicationEnhancer.bundle" and pressing "Return."


Type "reboot" and press the "Return" key, which will restart your computer in normal startup mode. According to the Apple website, the application will be gone from your hard drive.

Repair with an Additional Computer


Shut down your computer by pressing and holding the "Power" button until it shuts off, then turn it on again. Hold down the "T" key on your keyboard until the computer starts in Target Disk mode, which will display a blue or gray screen with a "T" icon.


Turn on the secondary Macintosh computer, then insert the FireWire cable into your primary computer.


Insert the other end of the FireWire cable into the FireWire port on the second Mac, then double click the volume disk icon on your secondary computer's desktop. Double click the "System" folder on the secondary computer, then double click the "Library" folder.


Double click the "SystemConfiguration" folder, then drag and drop the "ApplicationEnhancer.bundle" to the Trash icon on the secondary computer's dock.


Enter your system administrator password, and click "OK" to authorize the removal of the file. Drag the volume disk to the Trash icon on your dock to disconnect from the primary computer, and unplug the FireWire cable from both computers.


Press and hold the "Power" button on your primary computer to turn it off, then turn it back on in normal startup mode.

Items you will need

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