Disclaimer This is intended to be feedback based on my expereince this month with Avast 8, and not intended to be malicious or defamatory. However, I do get excited and my remarks sometimes get taken wrong.
I've just spent the last 4 hours downgrading to Avast 7. I think I finally have it downgraded and stable now. I do most of my real work (I write programs) in Windows 7 x64. I had difficulty with Avast 8 constantly urging me to update non-Avast programs on my system. My first attempt at trying out the new feature in Avast 8 resulted in a failed upgrade of flash, and I had to go direct to the Adobe site and do a new install of the latest version. The next update alert I received was for Acrobat Reader needing to be upgraded: the result was an older version of Acrobat was installed on my system.
I disabled the upgrade alert feature of Avast 8. Unfortunately, it didn't stay disabled. It kept re-enabling itself whenever the computer needed a reboot. The last straw was when I had an alert today for updating flash again, even though the update feature was no longer running.
I had read some of the complaints on the forum here previously about Avast 8, and there seemed to be an acknowledgement in general of these issues, and that an update was forthcoming. Well, there's been no signs of an update, and I've been fighting this thing for a couple of weeks now. If a program I wrote had caused this much of an issue, I would have halted work on all other projects and fixed it, free or not.
