I see above some mention Zone Alarm…not sure if everyone is same…
Another thread on the subject: http://forum.avast.com/index.php?topic=143107.msg1037766#msg1037766
An old thread…perhaps still not relevant but more FYI: http://forum.avast.com/index.php?topic=11486.msg97309#msg97309
Also, a suggestion may be if you are on other firewalls go ahead and change back to Windows FW and disable other to just test to see if helps.
…at least you can isolate issue.

Here is a full thread How-To on clean install: http://forum.avast.com/index.php?topic=143284.0
I mention/provide only because it is very critical to get rid of any other A/V remnants.
Perhaps V8 ran OK…but V9 may not…anyway, just a suggestion.
You may want to do a search in Program folder on HDD to see if there are other old A/V folders to isolate which cleaner you need to get.