I contacted the owner of the site (who happens to be my friend) and he was very surprised to say the least that his site was marked as malicious content by both Avast! and McAfee. I'm not technical but he explained that this could be related to the fact that antivirus sites often analyse the rating of the main domain and not the actual subdomain.
Compare http://www.google.com/safebrowsing/diagnostic?site=allfreebitcoins.pixub.com and http://www.google.com/safebrowsing/diagnostic?site=pixub.com

I am using Norton Internet Security myself and it never complained about it. Anyway, it's a different discussion and I'm not going to promote the url if it shows as malicious. Just wanted to warn people that many similar sites hosted with "bad" reputation domains could suffer from the same problem.