Sorry I can't help you cause I have exactly the same problem with JBOSS 3.2.3. I work with the Eclipse platform and JBOSS IDE 1.2.2
I think the DTD is bad but why ?
I have the solution:
You have to be sure that your jbosscmp-jdbc.xml rerefence the correct DTD (version 3.2):
<!DOCTYPE jbosscmp-jdbc PUBLIC "-//JBoss//DTD JBOSSCMP-JDBC 3.2//EN" "http://www.jboss.org/j2ee/dtd/jbosscmp-jdbc_3_2.dtd">