I had the same problem with crimson.jar. Seems like it's a problem with two XML factories in place. I replaced crimson by Xerces and now at least the server comes up.
for details (copied below).
To change JBoss to use the Xerces parser, you would need change the setup to that shown in Figure 13.31 assuming you copied the xerces.jar into the JBoss lib directory.
Figure 13.31. The run.sh setup for the Xerces xml parsers
# Add the XML parser jars and set the JAXP factory names
# Xerces parser JAXP setup