Exception when start Jboss 6 for JSF project

[blue0017]

Get below exception when start Jboss 6 for JSF project. This is the first time to use JBoss 6, i don't know how to config the project from JBoss 5.1 to Jboss 6.

My friend try to config it, but browser will popup window as download the home page file......

20:41:07,614 INFO  [org.jboss.as.osgi] (MSC service thread 1-2) JBAS011907: Register module: Module "deployment.pgs.war:main" from Service Module Loader
20:41:07,654 INFO  [org.jboss.weld.deployer] (MSC service thread 1-2) JBAS016008: Starting weld service for deployment pgs.war
20:41:08,339 INFO  [org.apache.catalina.core.StandardContext] (MSC service thread 1-2) The listener "com.sun.faces.config.ConfigureListener" is already configured for this context. The duplicate definition has been ignored.
20:41:08,340 INFO  [org.apache.catalina.core.StandardContext] (MSC service thread 1-2) The listener "com.sun.faces.config.ConfigureListener" is already configured for this context. The duplicate definition has been ignored.
20:41:18,489 ERROR [org.apache.catalina.core.StandardContext] (MSC service thread 1-2) Error listenerStart
20:41:18,489 ERROR [org.apache.catalina.core.StandardContext] (MSC service thread 1-2) Context [/pgs] startup failed due to previous errors
20:41:18,499 ERROR [org.jboss.msc.service.fail] (MSC service thread 1-2) MSC000001: Failed to start service jboss.web.deployment.default-host./pgs: org.jboss.msc.service.StartException in service jboss.web.deployment.default-host./pgs: JBAS018040: Failed to start context
at org.jboss.as.web.deployment.WebDeploymentService.start(WebDeploymentService.java:95)
at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1811) [jboss-msc-1.0.2.GA-redhat-1.jar:1.0.2.GA-redhat-1]
at org.jboss.msc.service.ServiceControllerImpl$StartTask.run(ServiceControllerImpl.java:1746) [jboss-msc-1.0.2.GA-redhat-1.jar:1.0.2.GA-redhat-1]
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110) [rt.jar:1.7.0_05]
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603) [rt.jar:1.7.0_05]
at java.lang.Thread.run(Thread.java:722) [rt.jar:1.7.0_05]

20:41:18,709 INFO  [org.jboss.as.server] (ServerService Thread Pool -- 28) JBAS018559: Deployed "pgs.war"
20:41:18,714 INFO  [org.jboss.as.controller] (Controller Boot Thread) JBAS014774: Service status report
JBAS014777:   Services which failed to start:      service jboss.web.deployment.default-host./pgs: org.jboss.msc.service.StartException in service jboss.web.deployment.default-host./pgs: JBAS018040: Failed to start context

[blue0017]

The project works fine using JBoss 5.1. Now it needs to upgrade to jboss-6.0.0.Final. i don't know which files need to change. Please help.