Discovered default username and password during the reading of the guide. If there are multiple users with their own login will this cause an error?

I’m new to Fog and the concept of it.
I have attempted to upload an image and get this message; TFTP server not found. I have installed the Fog Client on the computer I want to create the image from. I did a quick registration through the PXE menu. I have tried to push the image from the PXE menu and get requested for a password which I don’t know. The network admin told me the Fog server is the TFTP server. How can the TFTP server not find itself? The network admin doesn’t know what the password would be either.
The network admin setup the Fog server with Ubuntu 12. He said 10.04 was about to reach the end of its support and would like not to go backwards. Is there a major difference that causes this error? Is there a work around? I have no Linux background, so please explain your suggestions in a way I can present them to the network admin, he would like to see the world go Linux and drop Windows.