I'm having the exact same problem with a Japanese customer that I am trying to remotely provide support for. The problem is showing up in the /usr/sbin directory for me (I am trying to install a new version of some software and want to rename the old version as a fallback contingency)
I'm root (have "ssh"ed into the remote system, so should be no problem with permissions), and the filesystem is definitely read/write.
If anyone has any idea what could be going on, please post. I don't know of any permissions that would block root from doing stuff...