Confluence fails in Sun Application Server 8.1

After seeting the dabase configuration and creating the admin user I get the following cast exception when I hit 'Next'.

The following is the stack trace dump from Confluence:

Cause:
java.lang.ClassCastException: com.opensymphony.user.User

Stack Trace: [hide]

java.lang.ClassCastException: com.opensymphony.user.User
at com.sun.web.server.J2EEInstanceListener.handleBeforeEvent(J2EEInstanceListener.java:130)
at com.sun.web.server.J2EEInstanceListener.instanceEvent(J2EEInstanceListener.java:68)
at org.apache.catalina.util.InstanceSupport.fireInstanceEvent(InstanceSupport.java:189)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:192)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:178)
at com.atlassian.seraph.filter.LoginFilter.doFilter(LoginFilter.java:95)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:178)
at com.atlassian.johnson.filters.JohnsonFilter.doFilter(JohnsonFilter.java:96)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:178)
at org.springframework.orm.hibernate.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:170)
at bucket.custom.FlushingSpringSessionInViewFilter.doFilterInternal(FlushingSpringSessionInViewFilter.java:31)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:73)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:178)
at com.atlassian.util.profiling.filters.ProfilingFilter.doFilter(ProfilingFilter.java:132)
at com.atlassian.confluence.util.error.ProfilingAndErrorFilter.doFilter(ProfilingAndErrorFilter.java:27)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:178)
at com.atlassian.core.filters.gzip.GzipFilter.doFilter(GzipFilter.java:61)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:178)
at com.atlassian.core.filters.AbstractEncodingFilter.doFilter(AbstractEncodingFilter.java:36)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:178)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:263)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:551)
at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:225)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:173)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:551)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:551)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:132)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:551)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:933)
at org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:184)
at com.sun.enterprise.web.connector.grizzly.ProcessorTask.process(ProcessorTask.java:653)
at com.sun.enterprise.web.connector.grizzly.ProcessorTask.process(ProcessorTask.java:534)
at com.sun.enterprise.web.connector.grizzly.ProcessorTask.doTask(ProcessorTask.java:403)
at com.sun.enterprise.web.connector.grizzly.WorkerThread.run(WorkerThread.java:55)

Referer URL: http://localhost:8104/ConfluenceTest/setup/setupadministrator-start.action

Build Information:
Uptime: 1 minute, 33 seconds
Version: 1.4.2
Build Number: 214

Server Information:
Application Server: Sun-Java-System/Application-Server
Servlet Version: 2.4
Database Dialect: bucket.dialect.MySQLDialect

Memory Information:
Total Memory: 108 MB
Free Memory: 49 MB
Used Memory: 59 MB

System Information:
System Date: Wednesday, 24 Aug 2005
System Time: 20:16:32
System Favourite Colour: Lime
Java Version: 1.5.0_01
Java Vendor: Sun Microsystems Inc.
JVM Version: 1.0
JVM Vendor: Sun Microsystems Inc.
JVM Implementation Version: 1.5.0_01-b08
Java Runtime: Java(TM) 2 Runtime Environment, Standard Edition
Java VM: Java HotSpot(TM) Client VM
User Name: simstu
User Timezone: US/Eastern
Operating System: SunOS 5.10
OS Architecture: x86
Request

Information:
URL: http://localhost:8104/ConfluenceTest/500page.jsp

• Scheme: http
• Server: localhost
• Port: 8104
• URI: /ConfluenceTest/500page.jsp
• - Context Path: /ConfluenceTest
• - Servlet Path: /500page.jsp
• - Path Info: null
• - Query String: null

Attributes:

• javax.servlet.forward.request_uri : /ConfluenceTest/setup/finishsetup.action
• javax.servlet.forward.context_path : /ConfluenceTest
• javax.servlet.forward.servlet_path : /setup/finishsetup.action
• javax.servlet.forward.path_info : /500page.jsp
• javax.servlet.error.servlet_name : action
• javax.servlet.error.message :
• javax.servlet.error.exception : java.lang.ClassCastException: com.opensymphony.user.User
• com.atlassian.johnson.filters.JohnsonFilter_already_filtered : true
• javax.servlet.error.request_uri : /ConfluenceTest/setup/finishsetup.action
• javax.servlet.error.status_code : 500
• sessioninview.FILTERED : true
• com.atlassian.core.filters.gzip.GzipFilter_already_filtered : true

Parameters:

Logging: