What happened is they switched servers so they got a new IP address. IP addresses are mapped to domain names and routing is taken care of based on DNS(Domain name servers) throughout the net. The propogation of the new IP across all the DNS servers on the net will take up to 72 hours before all DNS servers. Until the server your ISP uses gets the updated info it wont be able to find the new site. The site is up and I could access it all day at work, but cant from home.