This could be due to few issues:
1. Your internet connection may be interrupted
2. Your IP address is block by our server
3. Your DNS configuration may be wrong.
The first step to solve is by using a website proxy to see if your website is loading fine.
Some of the web proxy samples are www.hidemyass.com, www.rxproxy.com.
Try to load your website from this proxy.
If your website is loading fine, then probably your IP is block by our server.
Send us your global IP address retrieved from http://whatismyipaddress.com/ and we will unblock your IP.
If you feel your DNS may be wrongly configured, please use www.intodns.com and input your website URL and see if there is any error reported.