I found this happened to us when we called Log4J's BasicConfigurator.configure() more than once.
Did you ever figure out what was causing this error? I can't find any more information anywhere on the net. I just started seeing this error today. Our app works like a champ on 2.4.4 with tomcat 3.2.3. With 2.4.6 and 2.4.7 with their respective catalinas, we get the same error message. The app seems to run, but there is no logging at all after the log error occurs. I also just tried 2.4.6 with Jetty and got the same error.
Oof... my mistake. I had an old window open and didn't see the reply. Hopefully thats what we're doing wrong.
Thanks a bunch!