Linking to Web Page

I AM GETTING A UNABLE TO LINK TO WEB PAGE OR WEB PAGE IS CURRENTLY UNAVAILABLE MESSAGE.I am trying to connect to Web Site to access a class online and it is not available through a proxy server,so I have changed ISP’s and using IE5 when I log into the class room with password I am not able to view the page,The task bar reads waiting on reply and the refresh will not bring the page up either.Any ideas why I cannot link to the Site.
I have tried deleting the cache and rebooting with no success.