Websites not loading

[ITBOB]

I have a site on a Windows 2008 domain. Over the last couple of days some websites will not load. They simply sit with the loading icon spinning in the tab. If you google search for the site it displays in the results but will not load.

 

There is a Sonicwall TZ 105 but I cannot see anything in the logs about sites being blocked.

 

If I enable a proxy all sites load fine, however the main application users use will not work.

 

I've restarted the DNS service on the server, flushed the DNS cache on both the clients and server and also rebooted the client PC's, server and router. This happens on domain PC's, non-domain PC's and the server.

 

Not sure where else to look? Any help would be appreciated!

[win]

Have you tried a variety of browsers? Test it with chrome, IE, and opera

[ITBOB]

Yes tried chrome, and firefox and get the same issue.