As I just noted for someone trying to install forums, there was a bug in the MySQL password changing script I wrote. First make sure you have the proper info as per the help section (I know you say you did, but double check) and then try changing your password under user services. You can change it to something, then turn around and change it back. That should force it to set the proper one in MySQL now that the script is fixed. If that still doesn't work, let me know what settings you're putting in, and the exact error message you're getting.