For anyone using Avast there is a new version of the free software, Version5. If the ball in the bottom right of your screen is blue, you're still using the old version. V5 uses an orange ball.
Download here
http://download.cnet....-2239_4-10019223.html
It's much easier to register when needs be. Initially the new version overwrites the old one and you existing expiry date continues with V5. When necessary to re-register you complete the registration form and your software is automatically renewed without the need to cut and paste a new key.