Well, that's pretty unusual: I don't think I've seen this kind of thing with .DS_Store before. Were you adjusting properties of the root of the volume while doing your backup?
I'd restart the machine and give this another try, and if it still fails, you'll have to fix it in Terminal (because the file is going to be hidden), with the command:
You might want to copy/paste that to make sure you get it right.
Let me know if that helps.