Look for a file called my.ini (found in C:\) ..Delete this file
run winmysqladmin.exe (c:\mysql\bin)
the choose a username/pword screen should pop up...make a new one
Close it and run mysql.exe (c:\mysql\bin)
type
Code:
GRANT ALL PRIVILEGES ON * TO user@localhost IDENTIFIED BY 'pass' WITH GRANT OPTION;
Replace user w/ the new username you picked and pass with the new password you picked
that should fix the rejecting of your mysql username / pword.