This problem occurs when the following conditions apply:
The J2EE Agent and Access Manager are on the same machine.
The agent is running in J2EE_POLICY mode.
The application being accessed is protected by form-based declarative security.
This specific configuration results in an error message primarily because of a bug in Internet Explorer 6.0 SP1, which cannot properly handle redirection when the HTTP request contains a port number. More specifically, this browser does not update the host header to reflect the new port number when you redirect HTTP requests that contain a port number.
Workaround: If the browser used to access content protected by a J2EE agent is Internet Explorer, at a minimum, the version must be Internet Explorer 6.0 SP2.