TCP/IP settings, into AWC, won’t mess avast installation. It’s difficult to say if any of AWC changes messed it, there are many changes. Maybe you could post a screenshot of the system and registry proposal changes before doing anything.

To know how to post a screenshot, see http://forum.avast.com/index.php?topic=8982.0
You can use Gadwin PrintScreen to get a screenshot (http://www.gadwin.com/printscreen/) or the free version of WinSnap 1.1.10 (http://www.filehippo.com/download_winsnap/?2173).