I have exactly the same problem, though my computer is on Windows 7 Business ed… Avast is not updating since yesterday 29th June. Luckely my virus data definitions were updated on the 28th. I have tried doing what SKY said (“Direct connection/No proxy”) and still does NOT work. I feel really uncomfortable as my computer virus protection is not up-to-date. Any help will be truly appreciated before I reinstall avast or get another anti-virus. Thanks from Spain