after install, message: Error-Invalid User Name

I have installed the WordPress progam supplied by IPower.com. After installing, I opened the readme file and followed the instructions, but found that the wp-config.php file already contained all of the necessary information requested in the wp-config-sample .php (I guess this program already searches out the needed info). I confirmed the database name, user name, and host with phpMyAdmin. I changed the password of my database, and made that change in wp-config.php also, but still get the same error message about invalid user name.
I searched your forums and found a lot of unresolved posts concerning this, but nothing in the resolved postings that I found answered my problem. There must be a lot of versions of WordPress because some posters talk about getting emails, which I never received, and no one talks about this program that autofills the correct info.