This turned out to be the solution...
The problem is on Geocities side. For some reason they are blocking our proxy server. You can access their sites with Internet Explorer by disabling the proxies.
To Turn the Proxy Server 'OFF':
Using Internet Explorer
· Open Internet Explorer
· Select 'Tools', 'Internet Options', 'Connections'
· Click 'LAN' Settings button at the lower right corner
· Uncheck options under 'Automatic Configuration' and 'Proxy Server'
· Click 'OK'
· Click 'Apply', if available
· Click 'OK'
· Click the 'Refresh' button (Next to the 'Home' button)
Using Netscape
· Open Netscape
· Select 'Edit', then 'Preferences'
· Double-click 'Advanced', in the left menu
· Click 'Proxies'
· Click to change the setting to 'Direct connection to the Internet'
· Click 'OK'
· Click the 'Reload' button (Next to the 'Home' button)