You're welcome.
Well avast doesn't set itself up to for anything, the web shield uses a localhost proxy to scan http port 80 content, before it is viewed on your browser. So outside of that no other change is made so that shouldn't have any impact on updates.
The avast Program Settings, Update (Communications), Proxy button, is usually set to Auto detect (use Internet Explorer settings). So unless Internet Explorer is set to use a proxy then again there should be no changes made by avast. So this is very strange.