Hello mate,
Had the FOG issue: Warning: mysql_connect() [function.mysql-connect]: Access denied for user ‘root’@‘localhost’ (using password: NO) in /var/www/fog/management/index.php

This is caused by the FOG PHP session looking to connect to ‘localhost’, the correct password is not being passed causing the failure. Not having time to research the exact fix I found the following is a quick solution…

Before trying to open the FOG management webpage
Install PHPMYADMIN (this makes database management easy)
Open //localhost/phpmyadmin
Create a new user and give them ALL permissions for ALL HOSTS (basically they should be the same as ROOT
Check the user is there and the permissions are set correctly.
Go into the PERMISSIONS tab and remove the password for ROOT under localhost & 127.0.0.1
Open the FOG webmanagement page
Set up the users in FOG
Go back to PHPMyAdmin and make sure FOG has been added as a database. You will need to log on as the ‘new user’ above
Reset the root password to something secure (as per pre install???)
Open the FOG database
Go to Permissions and BLANK the root password for localhost & 127.0.0.1
That should solve the issue.
Best regards
Arso