Mac OS X > Unable to read from or write to a DVD

A few weeks ago I wanted to watch a movie. Inserted a DVD and got an error from the DVD player. It was a strange situation because I had already seen a couple of movies, as well as written blank DVD disks.

Explanation: After updating the operating system, some permissions are damaged, so the operating system is unable to interact properly with DVDs.

How to Fix it?: Open: Applications > Utilities > Disk Utility, then select your hard disk (usually the first drive from the left-hand menu). Once selected, click the "Repair Disk Permissions" button.
You'll be able to see the following output from the "Log" icon at the upper-right hand corner of the window:

**********
Aug 27 11:31:26: Disk Utility started.

Repairing permissions for “Macintosh HD”
Determining correct file permissions.
Group differs on ./private/etc/authorization,
  should be 80, group is 0
Owner and group corrected on ./private/etc/authorization
Permissions corrected on ./private/etc/authorization

Permissions repair complete

The privileges have been verified or repaired on the selected volume

Try again, everything should be right. Seems to be an update error from the guys at Apple.