Into the firewall settings, the following programs should be allowed to connect:
C:\Program Files\Alwil Software\Avast4\ashWebSv.exe (avast! Web Scanner) (allow server rights; access to ports 80, 443; accept connections from localhost on ports 12080)
C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe (avast! e-Mail Scanner Service) (allow email rights: outgoing on ports 110, 25 and 119; accept connections from localhost on ports 12110, 12025, 12119)
C:\Program Files\Alwil Software\Avast4\Setup\avast.setup (avast! Update executable)
Don't need rights to connect:
C:\Program Files\Alwil Software\Avast4\ashServ.exe (avast! antivirus service)
C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe (avast! Update Service)
Last days we had a program update, so the firewall should ask you if you allow the 'new' (updated) components to connect.