Website blocked for no reason! help

Hello

this is my first post here and any help would be great, My wife has made a website for a local youth employment center http://www.yescentre.ca/

The thing is no computer at the center can see it, there is no fire wall problem and the HOST file on ever computer is empty including the server

I have not been able to see any router settings as they password protected, ( i’m not sure if a router can block websites). public proxy does work for a time, and the site is viewable across the country, All my research tells me the problem is located in that network , not the ISP, or host file .

All pc are running XP

Thank you