I changed my Gizmo5 password using N800. As a result, the presence icon turned red, from green. This is why I suspect password issue is the cause: although I can log in using my new password, if I try to change password again, I get an error message saying that my old (i.e. the "new" one that got me in) password is incorrect. If I know where the password file is stored, perhaps I can delete and start from scratch?
I received prompt response from Gizmo5. They are aware of some problems with case. I was instructed to experiment with entering my password in lower case. Just to be sure, I also cleared my registration. It worked.