Will give the suggestions a try. Another thought occurs:
This is the library on my main media server.
In another room I run MC 30, but often a few revs behind. When this started happening I recall when I was using MC in the other room to connect to my main library, it started to pop up a message that it was opening the library is "read only" mode. (I think that is what it stated). I think I had to close that message a couple times in a single session...
Could it be that something on that instance was affecting the library it was connecting to on my main instance?