It happens for me, only when I click on a webpages in my browser.
Now, I understand that Avast is trying to intercept viruses etc. when I visit webpages, but the fact that the Avast Account window pops up, suggests that Avast is trying to link that activity to my Account.
If this is the case and I suspect it is, I am extremely angry and disappointed.
Avast, you may have been rumbled here. If you are, please stop tracking my web activity, immediately!!