So you cannot see what I demonstrated on the screen shot I uploaded? There are many links on that page and the box appears on most of them, for 4/5 seconds and of course covering up what is underneath. Not a good viewing experience, as they say.

As I showed in the screen shot, there are no ticks but there are intrusive boxes.

No, the boxes appear when you move the mouse over a link. When avast is affect to look of a site to this degree I would say that it is more than simply a cosmetic issue.

My question here is - if I remove the extension will I lose browser protection?

Thanks for your response, BTW.