Thanks Whappo for the suggestion. I've been able to erase and to reformat the disks, but not in DVD+RW format. I had a look at the Imgburn site, including the instructions manual, and it does not appear to be able to do the job. Since I'd have to use the paid version of the software to presumably find out that it can't do the job I've decided to pass. It would also be cheaper to simply purchase replacement disks for the ones I've fouled up. I do however appreciate your reply and effort to help.