Thrown when an incompatible class change has occurred to some class definition. The definition of some class, on which the currently executing method depends, has since changed.
This might mean that you deploy a EAR/WAR/... that use libraries with change 'non-static' <==>'static' member.
A reason can be that your code is not compiled with the actual libraries
Actual libraries..? But 1 more thing all the jar files and packages what am using are used in another system. Its working fine there. Is this because of incopatibility of JBoss 5 with the JDK in my system? I have no clue wat is the cause.
Are you really using JBoss AS 5.0 version? If yes, then I would recommend that you move to AS 5.1.0 version and give it a try there. AS 5.0 had numerous bugs which were fixed in 5.1.0 and it's really not worth trying to figure out an issue while deploying on 5.0.