Have a Nexus 7 running 4.2. I am trying to simply copy files from one folder on the 'sdcard' to another and the copy fails each time.

Both folders have rw-rw-r-- access but the files won't copy either via a file manager (Astro or ES) on the device or via Airdroid (a web interface) or via 'Android File Transfer' app on my iMac.

I tried 'chmod 777' on them and that failed too! Renaming one of the files from .csv to .txt (to test for a different, unrelated error condition) could be done easily on the Nexus via ES File Explorer, for what that's worth.

What am I missing? It's been a long day and I'm a bit cross-eyed now...