Well for a start anything with a suite in the name I guess would have an AV element and if this is the case you should uninstall the AV element. This may require a complete uninstall of the suite and a custom install without the AV element.
I also believe the Security Suite comes with the Privacy function (?) that plays merry hell with the web shield in the past. If so you should have had a compatibility question when you installed avast about disabling the web shield transparent proxy ?
WEB SHIELD ISSUES - ZONE ALARM - also see bottom of page.
http://www.avast.com/eng/webshield_issues.html- Zone Alarm - avast! Web Shield compatibility dialogue - Install/Update Question - YES or NO
If you are using ZoneAlarm Free you should click NO, because privacy features are not present in ZoneAlarm Free this will not turn off web shield transparent mode proxy (Note the avast check should now be able to differentiate between ZA and ZA Pro so you may not see this interface if using ZA free).
Use a text editor and edit the avast4.ini file, the default installation location is C:\Program Files\Alwil Software\Avast4\DATA\avast4.ini (I would advise you copy avast4.ini before editing it, just in case).
If you answered incorrectly, Locate the line containing ZoneAlarmCompatibility= and delete that line (avast will ask again, answer NO) or change the value to =0. Save the edited avast4.ini file.
If you are using ZoneAlarm Pro and Privacy Control in ZoneAlarm is set to High and if you click YES in avast compatibility dialogue box the transparent mode proxy in web shield will be turned off you have to manually configure browser to access internet. To manually configure your browser watch instructional video
For IE - broadband users: -
Tutorial - Web Shield Proxy Set-up for IEFor IE - dialup users -
Tutorial - Web Shield Proxy Set-up for IE (Dial-up)For Firefox users -
Tutorial - Web Shield Proxy Set-up for FirefoxPersonally I fell that ZA is a poor firewall even the pro version doesn't do to well in tests.
See
http://www.matousec.com/projects/firewall-challenge/results.php.
See A Forum discussion on free firewalls
http://forum.avast.com/index.php?topic=30808.0