Problem with UsersRolesLoginModule

[sysuser1]

I am trying to secure jmx-console using UserRolesLoginModule and am running into some problems. I have uncommented the appropriate lines in web.xml and jboss-web.xml. When I access the page, the login dialog comes up, but it does not authenticate after entering the password. I found the following exception in server.log:

javax.security.auth.login.LoginException: unable to find LoginModule class: org.jboss.security.auth.spi.UsersRolesLoginModule
at javax.security.auth.login.LoginContext.invoke(LoginContext.java:631)
at javax.security.auth.login.LoginContext.access$000(LoginContext.java:125)
at javax.security.auth.login.LoginContext$3.run(LoginContext.java:531)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.login.LoginContext.invokeModule(LoginContext.java:528)
at javax.security.auth.login.LoginContext.login(LoginContext.java:449)
at org.jboss.security.plugins.JaasSecurityManager.defaultLogin(JaasSecurityManager.java:462)
at org.jboss.security.plugins.JaasSecurityManager.authenticate(JaasSecurityManager.java:417)


I have jbosssx.jar in default/lib directory, which has this login module class. Is there any configuration problem which is leading to this?

Thanks!

[sysuser1]

When I started the server using jdk1.4.0_01, it worked. Earlier I was using jdk 1.3.1_04 and was getting class not found error. Wondering if this is a classloader issue.
Are there any other known issues that one would face while running server on jdk 1.3.1_*?