Hi Jack,
Try this:
1) logout of WXforum.net (using the logout link at the top menubar).
2) clear your browser password cache for any entries for wxforum.net
3) clear your browser cookies for any entries for wxforum.net
4) click on the logon link for WXforum.net
5) enter your username and password and tick the "Always stay logged in" checkbox.
6) press the login button
Then you shouldn't be troubled with invalid password rejects again. Keep in mind, this is only for PCs that YOU have sole control over (never for a public PC, and not recommended for a Family PC).
Hope this helps, and best regards,
Ken