Symptom
iTunes does not successfully burn an audio CD on a USB CD-R drive if the burn speed is set higher than 2x.
Solution
You should set your USB CD-R drive to 2x burn speed when you make an audio CD. iTunes may not be able to successfully burn an audio CD at speeds higher than 2x on some USB drives. To set your drive to 2x speed, follow these steps:
1. Choose Preferences from the iTunes menu (Mac OS X) or Edit menu (Mac OS 9).
2. Click the Advanced tab or the CD Burning tab (depending on your version of iTunes).
3. Choose 2x from the Burn Speed pop-up menu.
4. Click OK.