Error 691: Access denied because username and/or password is invalid on the domain.
A. Verify the logon ID and password are correct.
B. Make sure the Include Windows logon domain check box is unchecked in the Options tab of the dial-up connection’s Properties dialog box.
C. Make sure the dial-up connection’s security option is correctly configured to use the Require secured password setting.
D. Delete all of the *.pwl files and reboot if you are using win9x.
E. Try another logon ID or create a new Logon ID because the profile may be damaged.
And if you encounter any problems feel free to comment / contact me.