System Error Code 5 Redux

As described elsewhere, I have been getting "Access Denied" with my nightly script for some time now. My script syncs my server running phpBB to my desktop. Typically, I get the error when attempting to delete a now empty directory because of an upgrade to phpBB. I have been manually deleting the directory, but this latest upgrade apparently remove a directory tree on the server, and so the error repeats on the next empty subdir, of which there appear to be many. So it's time to solve the problem.

I have followed the debugging guide described here, including the initial read/write test, but the error persists.

Relevant scripts and logs attached.
-Dan

Edit: example.bat was interactively executed in a CMD session, in directory I:\vps116136. I can, from this same user session, manually delete directories that report "Access Denied" when running the script.