Invalid MS-DOS Function error copying from UDF (DVD) to NTFS USB drive

Yes. I know there are many answers to this problem. Unfortunately I have tried as many as I can find and nothing works for me. Optimize, Defrag and Chkdsk will not work on the DVD-ROM and neither the Registry fix or the MS CD Hotfix work.

Specifically, I am trying to transfer RAW .NEF files from a backup DVD-ROM to an external NTFS USB hard drive using WIN 7. I get the above error. Strangely some of the .NEF files on that DVD have transferred properly, but not these in one specific directory, sorry two specific SUB directories. Actually the other subdirectories have .jpg and .mov files in them, so the file type is likely not the issue. Other .NEF files in other sub-directories have copied as well, so that does not seem to be the problem either. I have also tried robocopy from a Administrator-run CMD prompt and get an "Incorrect Function" error in that sub-directory. I am starting to lose hope.

It gets even more bizarre. On the DVD ROM, there are seven directories. All seven directories, and the files in them copied successfully. Three of them have sub-directories. I had thought that one of the sub-directories had copied completely, but it tuns out only 110 of the 132 files in that sub-directory copied successfully. The other 22 are giving the "Invalid" error. For the other two directories that have sub-directories, all the files in the directory copied successfully, while none of the files in the sub-directories copied successfully, although the sub-directories were created successfully, they are empty. This applies to the both the Windows copy and the robocopy attempts. There must be a clue in there somewhere.

Dougal

The story now gets EVEN more bizarre, worth y of the twilight zone. I came in this morning, put the DVD in the drive and attempted to copy again - and they all worked?! All the files that were giving me the "Invalid" error yesterday copied from the UDF DVD ROM to the NTFS USB external hard drive via Win drag and drop. I guess the problem is solved, but I have no idea why. I did nothing but run Recuva on the computer internal hard drive to see if any of those files were recoverable on it. None were. I can only think that the DVD drive is a bit 'touchy' about reading those double layer DVDs. Taking it out and putting it back worked, although I did try that before without success. Thanks for your comments. I made no sense that those files were corrupted and none of the others on that disk.

Further adventures. The copy function then started giving the error again. I have no explanation for why it worked once and not again before or after. I tried the disk in my laptop with a half height dvd drive (HL-DT-ST GU10N) and the same files copied perfectly. I suspect it is the drive on the tower computer (Optiarc AD 5170S). I guess I can either test it somehow or swap it.