Why won't my MacBook play DVD's???

what happens when you put one in? Does it spit it back out. etc?

The drive accepts discs but they do not mount or are automatically ejected

1. Check the disc's surface for scratches and dirt, since these things can prevent the disc from appearing on the desktop.
2. The MacBook Air SuperDrive is designed to be used with MacBook Air and Mac mini computers that do not have a built-in optical drive. For best results, connect the MacBook Air SuperDrive directly to the computer's USB port instead a USB hub.
3. Reset the System Management Controller (SMC).
4. Ensure your drive can read the specific type of disc being used. The System Profiler or System Information may provide additional information regarding what media your computer supports.
   • Mac OS X 10.6 Snow Leopard or earlier: Open Apple System Profiler by choosing "About this Mac" from the Apple () menu. Then, click More Info.
   • OS X 10.7 Lion or later: Open System Information by choosing "About this Mac" from the Apple () menu. Then, click System Report.
5. If the disc continues to not be recognized, contact Apple, an Apple Authorized Service Provider, or make an appointment with an Apple Retail Store for additional troubleshooting, evaluation, or service.

http://support.apple.com/kb/ht2801

welcome