There is a known issue regarding the allow/deny in the latest chrome that was released this week. See our post here: announcements/known-issue-with-chrome-21-and-unclickable-allow-deny-t12815
We have narrowed it down though. It seems that it happens when the publisher is on a fractional pixel in the layout. For example if the CSS sets the margin on any side to 0.5px, allow/deny will not be clickable. If it is on an integral pixel value, it works fine. We will be doing what we can to fix this in a release that goes out soon by using our JS library test for the layout position and only allow the publisher to sit on an integral value (or add the necessary margin if needed). That is why our tutorials work. Note: this can also be triggered if the element is centered (using something like margin: 0 auto;) inside a container with an odd pixel width because again its trying to render it at a fractional value.