Consider trying this ...
01. Locate and insert the 'MacOS X installation CD' into your Mac.
02. Reboot the Mac with the <option> key pressed (and kept pressed until icons of bootable volumes begin to appear). Once permitted click on the Installation CD's icon and then the '-->' button.
03. With 'Installer' launched select the 'Installer, Open Disk Utility...' menu item.
04. With 'Disk Utility' launched, click on the 'First Aid' tab, and then the 'Repair Disk' button (perform 'Repair Disk' at least twice).
05. Next, click on the 'Repair Disk Permissions' button (perform 'Repair Disk Permissions' at least twice).
06. Once finished (repair the disk and disk permissions) quit 'Disk Utility' and then quit 'Installer'. This will reboot (restart) your Mac.
07. Use the Mac, determining whether or not all is now working correctly - including 'iChat', 'Dashboard', and 'Finder' (in emptying the trash can).