ie7 no access random websites

I have vista x64 and using the 32 bit or 64 bit versions of IE7 I cannot access certain websites (one site I wanted to access for my email is www.orange.net, www.orange.co.uk works fine untill I try to log in for my email!), says no connection available, you are not connected to the internet or the site is down, blah blah blah!
A quick install of firefox and I can access these sites, is this vista or IE7?

I have the same problem. Only Google works for me so far. Dell, yahoo, microsoft,msn,firefox, foxnews, don't work. Windows update doesn't work either.