I am having similar problems and have done all of the above. I have run all the Cron Scripts via Cocktail, repaired disk permissions, verified and repaired the hard drive using 'fsck . . . ' , run the most comprehensive ram tests using Apple's diagnostic disc plus Memtest which all report healthy ram (as if I didn't know it after running the iMac on the same 1024Mb ram configuration for going on 3 years) and cleared the Pram. I also reduced the speed to 1. I have attempted to copy from my G4 iMac with SuperDrive to my new d2 Lacie DVD RW Dual Layer. I have had errors on two Dual Layer Disks 'Mac OS Error. Result Code = -5001.' This happens just at the end of the 'Writing Lead-Out' which must be just before the verification process. I have also now had four Single Layer DVD's fail at the Verification point with these bad sector errors or whatever you call them. I have tried a number of ways such as first making a disk image so that the burning would be straight from hard drive to DVD Writer. But I get the same #$^@ problem of failed verification. Even if a disk appears to work after failed verification, it will be unreliable, failing to read certain bits of data that you cannot manually check in any practical sort of way. When you need some data in the future you will end up not being able to read that bit of data and your DVD drive and computer will lock up/hang. So verification is absolutely essential. But now what I have just discovered is that the burning process completes perfectly if I use the internal SuperDrive on my G4 iMac. It has just finished. So the problem must be with these external devices like the Lacie d2 DVD RW etc. I have all the latest software and firmware updates so I am at a loss and I do not wish to waste more DVD media that cost money, especially the Dual Layer DVD's. Any informed advice, suggestions before I decide to return the drive on the grounds that it fails to do what it claims to and what I bought it for.