Using the Repair Privileges Utility
Most users of Mac OS X have not intentionally modified privileges and simply need a utility to reset system privileges to their correct default values. If you have Mac OS X 10.2 and later, this utility is included in the operating system.
For Mac OS X 10.2 or later, open Disk Utility (/Applications/Utilities/). Select your Mac OS X startup volume in the column on the left of the Disk Utility window, then click the First Aid tab. Click the Repair Disk Permissions button.
If you have modified the contents of the folder /Library/Receipts, the Repair Permissions feature won't work as expected. Repairing permissions requires receipts for Apple-installed software. Additionally, the utilities only repair Apple-installed software and folders (which does not include users' home folders).
The remainder of this document contains more advanced information.
Note: In Mac OS X 10.5 and later, while started up ("booted") from the Mac OS X 10.5 installation disc, a user's home directory permissions can be reset using the Reset Password utility.
Warning: This document describes how you may modify permission settings by entering commands in the Terminal application. Users unfamiliar with Terminal and UNIX-style environments should proceed with caution. The entry of incorrect commands may result in data loss and/or unusable system software. Improper alteration of permissions can result in reduced system security and/or exposure of private data.