Using CDRW as a disk drive has proven to be finicky over the years. While it does work most of the time I've seen too much loss to call it ready for production.
Try a new disk of another make.
Bob
Few weeks ago this happened on CD-RW. Last week OK - huh?, another problem solved in Vista. Bought new CD-RW today and back to square one. The drive backups OK, burns OK. What's up? Thanks.

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