To my dismay only the users who are using AVAST antivirus cannot enter the site, because AVAST is tenaciously disabling it.
As I figured out, probably some other users who were using pixub.com subdomain had viruses on their pages so AVAST probably just blocked the whole domain.
Keep in mind that I have nod32 antivirus and I have tested dozen other free solutions - none of which is reporting any viruses.
How can this happen? How can AVAST be contacted to remove the ban?
If you believe your site is free of any malicious code, you can request avast to allow it through the contact form: http://www.avast.com/contact-form.php