I am running CB nightly build from a few days ago, 4281, but it doesn't look like this issue has been addressed.
Settings -> Environment -> General Settings -> "Check for externally modified files" is enabled, however when I modify files with an external editor and switch back to CB editor, the file does not display with the updated content. I had previously been using RC2, and this feature worked fine. When I would switch back to CB, I would get a prompt that files had been modified, would I like to refresh, etc.
This is my first install of a nightly build, so I don't know how long this feature has been broken/changed.
I am running Win XP SP2.
UPDATE: nevermind, after I quit the project and reopened, everything seems to work correctly. CB was definitely misbehaving for a while, but I could not repeat the error.