<p>This problem was <a href="http://meta.math.stackexchange.com/questions/1323/slow-processing-different-look-to-math-processing-problem-with-fonts-is-it-me">first reported</a> on Math.SE. I'm bring this to your attention since Stats.SE also uses Mathjax.</p>

<p>Basically, the latest build of Firefox version 3.6.13 has a known issue of messing up Mathjax font(to the point where the font doesn't load). The devs of Mathjax are <a href="https://github.com/mathjax/MathJax/issues#issue/22" rel="nofollow">aware of this</a>, and are working on a fix.</p>
