Symptom
When you try to restart the computer, an alert box appears with the following message:
"The startup disk no longer has a valid System Folder.
"'System' and 'Finder' must be in the System Folder. If you continue, you may not be able to restart the computer. Do you want to continue?"
You may also find that some fonts displayed on screen have jagged edges, and the items in the Apple menu after "About this application..." may not be present.
Solution
Important: This solution deals with the Mac OS 9 "System Folder". When Mac OS 9 and Mac OS X are installed on the same computer, there is another folder at the top (root) level of the hard drive named just "System". The System Folder contains Mac OS 9 software components, and the System folder contains Mac OS X software components. Do not confuse the two folders.
The symptom can happen if:
- The System and/or Finder files are not in the same System Folder.
- The System and Finder files are damaged.
- You are using versions of the Startup Disk control panel earlier than 9.2 to select a Mac OS X startup disk.
Note: You should use Startup Disk 9.2.1 or later.
Choose a set of steps to match your situation (A or B):
A. Use these steps if you are starting up alternatively from Mac OS 9 and Mac OS X and your System Folder otherwise appears to be intact.
1. Click the Cancel button in the alert box if it is still on screen.
2. Download Startup Disk version 9.2.1 or later from Apple Software Downloads (http://www.apple.com/swupdates/).
3. Use the this version of Startup Disk to select the Mac OS X disk.
You should no longer see the alert message when restarting.
B. Use these steps if you are not using Mac OS X or if you suspect your System Folder is not intact.
1. Click the Cancel button in the alert box if it is still on screen.
2. Locate the System Folder. It is normally at the top level of your hard disk, but it might have been moved or renamed.
3. If you have located the System Folder, open it and check for the presence of two items, named "System" and "Finder."
4. If these files are not in the folder or you cannot locate the System Folder, use Sherlock to locate "Finder" and "System." (This may also allow you to locate a System Folder that has been renamed or files that have been misplaced). As necessary, return the name of the folder containing your system software to "System Folder" and/or put the System and Finder files back into this folder.
Note: Depending on the state of your System Folder, you may not be able to open Sherlock using the Apple Menu or Command-F keyboard shortcut. In this case, you can start up from a Mac OS 9 CD-ROM disc to use Sherlock.
5. Double-click the System file.
Replacing the files in the System Folder or double-clicking the System file should re-bless (reactivate) the System Folder. You can tell a System Folder is blessed when the Mac OS logo badge appears on the folder. If the System Folder is not re-blessed by this point, you may start up from a Mac OS 9 CD-ROM and use Disk First Aid to verify and repair the hard disk. You may also need to reinstall the core Mac OS 9 operating system.
Note: A Mac OS 9 System Folder used for the Classic environment must be reinstalled by the clean installation method. See technical document 106294: "
Mac OS X 10.0: How to Reinstall Mac OS 9 or Recover From a Software Restore"