Thanks, Dave. I'd looked at the Troubleshooting section of the UG but I think it had just been too long a day staring at screens and I didnt pick up on the duplicate and replace technique. At that time I was not seeing any I/O errors, but subsequently I've seen plenty of them. Appears my MBP has a logic board problem causing power levels to usb & fw bus-powered drives to dive (usb drives wont mount and fw gets tons of i/o errors).
But I am curious, can you give any insight to the Invalid Argument error? What's happening specifically that causes SD's copy statement to have one? I was a bit mislead (not to say flummoxed
.
-K