IE won’t connect but Firefox connects fine

IE (version 7.0.5730.11) will not connect to internet, but Firefox is connecting without difficulties. I have tried shutting down Zone Alarm, Counter Spy and McAfee (virtually eliminating all my safeguards) and IE still does not connect. The message is that “Internet Explorer cannot display the webpage.” However, when I click on “Diagnose Connection Problems” I am told that the connection is working fine and no problems are detected.

I have verified that there are no proxy settings or anything else that I can think of.

Of course I have rebooted but the problem remains.

Grateful for any advice and help.

Oh yeah–running XP Pro.

Thanks for any advice!