deployment descriptor xml files error

[sadfeen]

I am getting the following error everytime I open an xml descriptor file like eb-jar.xml or jboss.xml

An internal error occurred during: "loading http://java.sun.com/dtd/ejb-jar_2_0.dtd".

I am following the tutorial listed here: http://docs.jboss.com/jbosside/tutorial/build/en/html/deployment.html

Due to this problem, my application does not function via the browser.

Any idea?

Thanks.