Happened to me. From Git Bash, on Windows 8 running Docker Toolbox. There are two things happening. From git bash, we do not seem to have complete escalated privilege to the docker daemon (even though i'm running git bash with administrative privileges).
Thus:
Try running the command from your docker terminal. (gives you privilege).
To compensate for errors from Window's folder naming formats, don't forget to quote the path.. (to escape spaces and/or capitalization errors) say
From:
docker run -v $(pwd):/data image_ref
To:
docker run -v "$(pwd):/data" image_ref
(notice the enclosing quotes in the latter around $(pwd):/data).
