Use these steps if your computer experiences a blue screen, broken folder icon, gray screen, kernel panic, flashing question mark, or otherwise stops responding when starting up with Mac OS X.

• Mac OS X 10.0 and later
• Mac OS X Server 10.0.3 and later

1. Mac OS X reviews fonts in the Mac OS 9 System Folder during startup. A damaged Mac OS 9 font file may contribute to this issue. Start up from your Mac OS 9 System Folder or a Mac OS 9 CD-ROM disc. Drag the Fonts folder in the Mac OS 9 System Folder (not the Mac OS X System folder) out of the System Folder into the root level of the hard disk, or to the desktop. Restart the computer from your Mac OS X volume.

2. Remove third-party startup items.
a. Start up from your Mac OS 9 volume or a Mac OS 9 CD-ROM disc.
b. Navigate to your Mac OS X volume.
c. Temporarily remove third-party items from the /Library/StartupItems and /System/Library/StartupItems folders. You may wish to temporarily store items in your Mac OS X Users folder. If you are unsure whether an item is a third-party item or an Apple-installed item, do not remove it.
d. Restart from your Mac OS X volume.

3. Otherwise, follow the steps for Symptom 1.

4. In some instances, setting auto-dial may interfere with the login process. This option is set in the Networking control Panel under PPP Options by checking the "Connect automatically when starting TCP/IP applications" box. This setting can be removed from single user mode by removing the preferences file that holds the setting. Note: This is an advanced step. This will reset all network settings to default. You will need to reconfigure the Network pane of System Preferences to reconnect to the internet or your network.

a. Start up in Single-User Mode (press and hold the Command-S key combination during startup until white text appears).
b. Type: mount -uw /
c. Press Return.
d. Type: mv /var/db/SystemConfiguration/preferences.xml preferences.old
e. Press Return.
f. Type: reboot
g. Press Return.

5. Reset certain privileges. Note: This is an advanced step:

a. Start up in Single-User Mode (press and hold the Command-S key combination during startup until white text appears).
b. When the command line appears, type: fsck -y
c. Press Return.
d. Type: mount -uw /  
e. Press Return.
f. Type: chmod 1775 /  
g. Press Return.
h. Type: reboot
i. Press Return.

1. Renaming or relocating system-installed folders may lead to a startup issue or kernel panic. Do not relocate system-installed folders (such as Applications, System, or Library) while started up from Mac OS 9, or logged in to Mac OS X as the root user. If you have moved or renamed system-installed folders, you should return them to their original location or rename them using their original names. See technical document 106805, "Mac OS X: 'Broken Folder' Icon or Kernel Panic When Computer Starts Up".

2. Modifying the privileges of Mac OS X system files may contribute to a kernel panic. See technical document 106428: "Mac OS X: Changing Privileges for System Software Components May Prevent Proper Startup"

3. Hardware associated with kernel panic

Certain hardware may produce a kernel panic message during startup. See the documents below if you have the named hardware:

Technical document 106422:
"Mac OS X 10.0: Kernel Panic When Using Matrox RTMac Card"

Technical document 106404:
"Mac OS X 10.0: 128-Bit 2D/3D Professional Graphics Card Causes Kernel Panic"

4. Otherwise, follow the steps for Symptom 1.

1. Make sure that the current firmware for your computer is installed. The latest firmware updates are available from Apple Software Downloads (http://www.apple.com/swupdates/).

2. Disconnect peripheral devices, except for the Apple keyboard and mouse. This includes ADB, serial, USB, FireWire, SCSI, and PCMCIA devices. If this resolves the issue, add back one device at a time, restarting after each, to isolate the issue.

3. Remove third-party hardware upgrades such as memory (RAM), microprocessor upgrade cards, and PCI cards. If this resolves the issue, add back one at a time, restarting after each, to isolate the issue.

Note: Apple does not provide technical support for Mac OS X when used with third-party processor upgrade cards.

4. Try using Disk Utility or, if necessary, fsck. See technical document 106214: "Mac OS X 10.0: Why, When, and How to Run fsck for File System Maintenance"

1. If an Ethernet cable is connected, temporarily disconnect it and restart.

If you have enabled NetInfo, you may need to temporarily disable it with the Directory Setup application.

2. "If you have previously removed or renamed any of the following Mac OS X system files or folders, see Technical document 106805, "Mac OS X: 'Broken Folder' Icon or Kernel Panic When Computer Starts Up".

• Applications (a visible folder)
• automount (an invisible folder)
• Library (a visible folder)
• mach_kernel (an invisible file)
• System (a visible folder)
• Users (a visible folder)
  
3. Otherwise, follow the steps for Symptom 1.

Technical document 106805:
"Mac OS X: 'Broken Folder' Icon or Kernel Panic When Computer Starts Up".