Any firewall?
Other security programs that could interfere?
Can you test with “no proxy” setting (Updates > Proxy)?
Which was your old antivirus (before avast)?
hi!, I have the same problem as yours… I just uninstall my avast antivirus and reinstall it, (but don’t install your old one,) download the latest engine of avast and register it again (if you are a home user)… After that my avast works perfectly… I hope this will help… Thank You!