Can you please clarify the following: Do you mean you cannot put your cursor into a field on the registration page because of a browser popup asking if you want to see notifications from this community?
Also, what browser are you using and do you have any extensions installed in it?
Same entry in logs. The header content contains invalid characters. We've tried to add МойОфис both manually and via copy/paste so there's no possibility of adding some special symbols exept cyrillic.