Could be a settings issue, but we probably need a bit more info.
Did you have to disable Avast to download the files I linked you to?
How does your computer connect to the net normally?
What is the Operating System, and the make of the computer? Desktop or laptop?
Can you connect at all, using any program, or is it completely disabled, when Avast is running? (What programs have you tried to connect with. I'm assuming just a browser.) Other programs that require net access are Avast itself, for updates, and an email client, like Outlook Express, for example. Please try manually updating Avast and see what happens.