medium write error

Hello topjock,

Thank you for providing the details of the burning issue you are experiencing. I found some resources that I think might help:

First, I recommend resetting the System Management Controller (SMC) on your Mac:

Resetting the SMC on Mac portables with a battery you can remove

Note: Learn about removing the battery on MacBook and MacBook Pro.

1. Shut down the computer.
2. Disconnect the MagSafe power adapter from the computer, if it's connected.
3. Remove the battery.
4. Press and hold the power button for 5 seconds.
5. Release the power button.
6. Reconnect the battery and MagSafe power adapter.
7. Press the power button to turn on the computer.

Resetting the SMC on portables with a battery you should not remove on your own Note: Portable computers that have a battery you should not remove on your own include MacBook Pro (Early 2009) and later, all models of MacBook Air, and MacBook (Late 2009).

1. Shut down the computer.
2. Plug in the MagSafe power adapter to a power source, connecting it to the Mac if its not already connected.
3. On the built-in keyboard, press the (left side) Shift-Control-Option keys and the power button at the same time.
4. Release all the keys and the power button at the same time.
5. Press the power button to turn on the computer.

Note: The LED on the MagSafe power adapter may change states or temporarily turn off when you reset the SMC.

You can find the full article here:

Intel-based Macs: Resetting the System Management Controller (SMC)

http://support.apple.com/kb/HT3964

If you are still having trouble with burning after that step, I recommend reviewing the section titled "Top troubleshooting tips" in the following article:

Disc Burning Quick Assist

http://support.apple.com/kb/HT1152

Thank you for posting in the Apple Support Communities.

Best,

Sheila M.