Ok, this should go to the developers, actually, but I can't find the easy way to contact them, so I've decided to share this with all of you, until the problem gets solved.
I was reinstalling windows on this one computer, and everything went smooth, until I installed Avast. In fact that went smooth too, but I couldn't register it. When I click on register button, a small pop-up window appears, saying "Retrieving information..." and it stays there for couple of seconds, after which disappears and nothing happens. I've tried to request a serial number on mail, that went smooth, but when I enter it into the required field - still nothing happens.
After 2 days of trying to find what the problem is, I finally gave up, and downloaded AVG. After I installed it, during the update process, AVG points out that there is a problem with system time. Only then I realized that the time was set to year 2025. I couldn't believe that THAT was the problem, but I had to try again. I reinstalled Windows from scratch again, and reinstalled Avast and now everything is all right.
So the point of this thread is to alert developers about this flaw. If the system time is set to some time in the future, Avast can't register! I believe that's not a big issue to solve, and you'll probably spare someone the torture I had to go through.
Thanks.