I recently installed phpMyAdmin with MySQL, it works fine, allows the root to login via the website, but when I attempt to create users and give assign them to a database, it gives me the error "#1045 Cannot log in to the MySQL server". This server is running on CentOS 5.8.
Ensure the credentials in the phpMyAdmin configuration are correct and that it is pointed at the correct server. You may also check your mysql logs (possibly in the system logger but generally
Remember that phpMyAdmin's login is separate from the mysql login.