can't download virus defenses

for some odd reason I can’t download updates on virus defenses I tryed using different connections but it doesn’t work it just says unknown error

  • Which Avast…? (Free/Pro/IS/Premier)
  • Which version…?
  • OS…? (32/64 Bit…? - which SP/Build…?)
  • Other security related software installed…?
  • Which AV(s) did you use before Avast…?

What operating System ???