For some reason, Macs have a tendency to forget who can open, read, or write to what file or folder and who has what permissions. You might have even seen errors relating to this yourself, with your Mac complaining that a specific file doesn’t belong to you when clearly it does. Whether you’ve seen these errors or not, you can prevent them from ever occurring and resolve them if they have occurred by using Apple’s Disk Utility. You should also scan the hard disk for errors once a month, just to make sure there are no problems.
You should run Disk Utility two or three times a year for prevention’s sake and whenever you receive a permissions error. To run Disk Utility, follow these steps:
1. Open Applications>Utilities>Disk Utility.
2. Select your startup disk from the list.
3. Select the Disk First Aid tab and then click Verify Disk Permissions.
4. If you receive errors, click Repair Disk Permissions. (You can just as easily skip step 3 and go directly to Repair Disk Permissions.)
You can boot your Mac using your Mac OS X CD and access the Disk Utility too. There, you can use Disk First Aid to verify permissions and also scan the hard disk for errors. Disk Utility checks the Overflow files, the Catalog file, multi-linked files, and the Catalog hierarchy. It also checks volume information and can be used to repair problems it finds.