This issue has bowled me over. I am using JWS 1.4.2_08 and I am able to connect to development and Quality XI box. But when I try to connect to the Production XI Box I get an error message "Authentication Error: Unknown username or wrong password". Now I am able to access SLD, RWB using the same logon details and also I am able to logon using SAP GUI. I checked I have the XI_ADMINISTRATOR & XI_DEVELOPER roles assigned to me.
But still I cannot connect to production XI system from my machine, but using the same logon details I can logon from my friend's machine to the production XI box.