You should really keep these together
http://forum.avast.com/index.php?topic=17737.msg150885#msg150885.
I too have no problem with access to the avast.com web site.
What is your OS?
What is your browser - have you tried a different one?
What have you done to try and resolve it?
Are you using any other security software that may be blocking the avast.com web site?
What is your firewall, does it show anything in the logs to indicate why it is blocked?
Have you checked your hosts file to ensure it isn't blocked there?