This is a typical error message when an invalid password is set for the user. This error message also means that that user is ignored by the system.
The user account information in MySQL servers are hold in "user" table of "mysql" database. Modifying the "user" table for that user account with a simple SQL command will solve the problem.
UPDATE user SET password = PASSWORD ('(NewPassword)') WHERE user = '(Username)' AND host = '(Hostname)'
