Check your CLASSPATH "jnet.jar" must be missing.
I too had faced a similar problem.
It was solved when I added all required jar files in CLASSPATH
thank you very much priti, i was able to get rid of that error, but now i have other error of Exception in thread "main" java.lang.NoClassDefFoundError: org/jboss/logging/Logger...
let me try by adding log4j.jar ..it seems there is a bug in lo4j.jar module of Jboss 3.0...(not sure...please confirm)....
thanking you again,