I solved my issue. I was getting the error above because I installed JBoss SOA-P into a vmware "SharedFolder" that is shared with the Windows 7 host. After moving the installation to /opt on the local disc for the Linux server the issue did not come up.
I was getting more deployment errors after but after following this guide: https://community.jboss.org/wiki/DroolsGuvnor50InJBossAS5 I removed the following jars from the drools-guvnor.war and drools-guvnor is working in JBoss SOA-P 5.3.1:
- ./WEB-INF/lib/xercesImpl-2.9.1.jar
- ./WEB-INF/lib/xml-apis-1.3.04.jar