In the last days, I always needed to refresh the page after I clicked on something like 1 new answer, or this post was edited, else mathjax didn't render the $\LaTeX$ code. About 2 weeks ago, when I started using SE it always rendered without loading the page again.
I use Google Chrome and I have windows 8, in the comments one mentioned the same problems on vista with firefox.
Here is an image of the error
N new answers
somehow escapes client-side scripts, and not only MathJax. Chrome 25/Win7. $\endgroup$