This is me geeking right out, folks, so feel free to skip ahead unless file retrieval makes you tingle.
So I burned a bunch of large files onto a DVD, using Nero. Nero reported that all was well, and when I checked the DVD, the files seemed to be there. Then I deleted them off my harddrive.
The next time I popped that DVD into the drive, though, it showed as blank, with a 0 size. Damn.
A closer look at the DVD with file recovery software indicated that the filenames indeed existed, but I still couldn’t pull them off.
So I scritched my head for a moment or nine, and here’s what I tried:
I opened Nero again, and told it to copy the DVD for me. Instead of burning the copied image to media, I saved it to my HD as an image file. Nero uses a file extension of *.NRG, which is pretty well the same as .ISO, so I renamed the file to image.iso, and then used WinRAR to treat it like an archive file, opened it up, and woo! there were all my files.
I extracted them safely to my hard drive, and will now live happily ever after.
And if Google has brought you here because you’re experiencing the same problem, I hope it works for you as well.