Select boxes just stopped working altogether in Firefox. Works fine in Chrome.

Something to do with font size or fontface? Had something like this before, cant quite remember the Solution.

@TobyAsE I'm not sure, but it might be a performance/memory issue. I did have many Firefox windows open at the same time, but it's still a mystery why FF performs so badly and uses up so massive amounts of memory. Have they not fixed the ancient memory leaks already?