You may recieve this error message when a web page you are trying to access no longer exists or is the incorrect address. Make sure the address you are typing in is correct. Try different variations of the address, such as: vance.net or www.vance.net or http://www.vance.net.
You will also receive this message if you try to access a web page while not connected to the internet. Verify that you are on the internet by the presence of 2 small green screens in your taskbar. Or click on your connection on the desktop and see if it says you're connected.
This message does not necessarily mean something is wrong with the internet service, just that the computer or web site you are trying to access has a problem or doesn't exist.
Links to more information:
Error Message "Error 645" Using Dial-Up Networking, Cannot connect to server