Error 691: Access denied because username and/or password is invalid on the domain.

Solution: 
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.

ENJOY.

And if you encounter any problems feel free to comment / contact me.