disk burner is in use by another application
I'd seen a number of old posts regarding this error. You try to burn a CD from iTunes, e.g. when you say "Burn playlist to disc". It says "please insert a blank CD". You insert a blank CD. It says "checking media" then immediately displays an error message, "the disk burner is in use by an application other than iTunes."
I appear to have solved my problem as follows:
1. Quit out of iTunes.
2. Insert a blank CD.
3. The Mac OS will give you a prompt asking you for the default action for what it should do when you insert a blank CD.
4. Choose "Open iTunes" and click the check box "make this action the default."
iTunes itself may give you a message then, when the CD is in the drive; just click "don't show this message again."
Then iTunes seems to burn CDs okay after that.
Clearly a long standing bug though; I've seen posts from 2007 and earlier; I'm on Mac OS X Mavericks.
Mac Pro, OS X Mavericks (10.9)