Problem with altervista or google ads with chrome

As the title says, I cannot display ads in a altervista web site.
Google Chrome is not able to show the ads.
Internet explorer and Nexus 10 tablet show the ads with no problems.

How is it possible to fix this problem in Chrome?

I run the last version of Chrome on a Seven operative system.

Regards.

[Gianluca]

Which extensions have you enabled in your browser? Have you any antivirus or firewall installed?