For one reason or another, I find myself occasionally restoring a MacBook from a Time Machine backup, or transferring my account from one Mac to another.  Afterwards, I inevitably receive the following error when attempting to watch an instant play movie:

Digital Rights Management (DRM) Error

Error Code: n8156-6013

We’re sorry, but there is a problem playing protected (DRM) content.

This usually occurs after migrating your settings to a new computer.  Please call Netflix at 1-866-579-7113.

The solution is to delete the following file and then try to play the movie again:

/Library/Application Support/Microsoft/Playready/mspr.hds

Good luck and enjoy those movies!