true indian, I already have scanned my computer with Malwarebytes, Kaspersky Virus removal Tool, Panda, Spybot SD. No problems found.
If you think that it's malware that can not be detected by any of these sowtware, how is it possible that this problem appeared on 2 computers at the same time? The same problem has 3rd computer which was off for several weeks. Last night I turned it on and tried to update Avast. The same problem - can't update.