Incorrect password/username after moving a site

I had to move a site to a new server. I followed the instructions I found to do so. The site shows up and works and the manager comes up. However, it gives me this error

Incorrect username or password entered!
Location: http://eldostorm.greatriv.com/manager/

However, I DO have the right name and password. The site I "copied" is still up, so I tried it and it works.

Thoughts on what may be the issue?

Try completely clearing your browser cache and removing all cookies for both domains.

Is the database of the old and the new site using the same character encoding?

If all else fails, you can edit the username and password in the database directly (make sure to apply the MD5 function to your new password; in phpMyAdmin there is a "function" drop-down to select from).