Before you try Norton:

You should seriously try Alsoft's Diskwarrior. It is honestly the absolute best program out there. It has saved my @ss on several occasions, this past Saturday being the latest. If you get serious errors that Disk First Aid says it can't repair, you need this app.

Other utilities can often do more damage and make things worse. DiskWarrior will actually let you preview what the "repaired" disk will look like. You can even check that "preview" disk w/ Disk First Aid to see that the errors were repaired prior to actually repairing the directory.

Check it out here:

http://www.versiontracker.com/morein...atings=&db=mac

Hope this helps....