Your post is pretty much lacking any detail that would allow somebody to help out. The only thing in there is the IllegalAccessException. (I assume it's an IllegalAccessException you're getting because I dont know of any other kind of IllegalAccess error... more detail pelase!)
Since you haven't thought to consult the Java API yourself, here's what it says about that exception:
Quote:
Thrown if an application attempts to access or modify a field, or to call a method that it does not have access to.
Normally, this error is caught by the compiler; this error can only occur at run time if the definition of a class has incompatibly changed.
So, there you have it. My guess is you have different builds of code running on different machines in either a cluster or on your EJB tier vs web tier.
Next time try posting a little more information (actually try posting ANY information)...