mysql sysadmin cookies issues

When I set cookies for users of my site I am getting the following error on some of my pages: "Could not connect: Access denied for user 'devtest'@'localhost' (using password: NO)" The user 'devtest' is not one of the users of the site but it is the owner of most of the php files and the account I use to ftp to the server. I don't understand why setting a cookie for users would be causing this but as soon as the cookie expires I no longer get this error. I've tested it extensively and it's definitely correlating with the cookie being set. 'devtest' is not the name of the db user either so I don't understand why its trying to use this user