Can't help with Avast as I don't use it. Other members do and will probably be able to sort your problems. If not and you want to give AVG 7 another go then I will try to help if I can.
Your correct in saying that AVG 7 has caused numerous problems but most have been sorted now. There have been a dozen or more threads regarding one issue or another with AVG 7 and its not quite as straight forward as AVG 6 was in setting up.
Version 6 was just a quick download and leave as it was to silently get on with its work. Version 7 needs a few tweaks depending on what the problems are.
If you can let us know what problems you were having with version 7 then we may be able to answer them before you make a decision to change back or not.