I am pleased to say that there is no problem. I had thought that Dreamweaver 4 had been broken but that is not the case. What puzzled me was that the Edit menu of the document window of Dreamweaver 4 took a long time to drop down. I am now of the opinion that Avast is not to blame (it does the same when I tried AVG, the less of which said the better - very slow performance). I just noticed the Dreamweaver behaviour coincidental with the installation of Avast 7.
I have given Avast 7 a good going over on a spare system drive and find that Avast 7 makes the system seem quicker including web access. It behaves well for me on my Windows XP Pro SP3 system.
I would be very pleased if Avast can make Script Shield work with Google Chrome (yes, Google Chrome is enabled in Script Shield main settings). It does work with Avast 6 on a more or less identical system to the test version I have been using today.
It takes time to absorb the differences in system behaviour. What I am learning is that Avast 7 is a job well done and I look forward to the little rough edges being smoothed in subsequent program updates.
As far as Outpost Firewall Pro 7.5.2 is concerned, Avast 7 seems to effectively disable the real-time antispyware feature but Web Control works properly. I conclude that Outpost Firewall works well with Avast 7 and that doing without Outpost real-time antispyware benefits performance.
My verdict on Avast 7: