Motf, two thoughts:
1. Only copy at 1x so that the CD Drive delivering the signal can keep up with the CD that's doing the writing.
2. Make an image of the audio CD on your hard drive first and then write the copy from that image. Then rub out the image if you don't want to make any more copies. It'll need 6-700MB free on the HD for the image and another 2-300MB for the overheads. So you probably need 1GB free.
Both of these measures considerably increase the time it takes you to complete the process, but it beats filling the waste basket with spoiled CDs.