Does you configuration file not use a Log4J CONSOLE appender? If not, that is the last line you will see printed on the console.
Regardless, if the above is the problem, JBoss is not hanging, it is now longing elsewhere.
I have the same kind of problems, but with only the basic file, behaviouring differently with the type of restart i use, or if i just add one category limitation.
I just think that after parsing the log4j file, jboss is not hanging, but has just a log misconfiguration problem. So if anyone has some tips about about how to tune the log file in a good manner, it'll be welcome...