I appears that its only 3.1, and yes, it happens on both windows and mac. I can confirm it does not happen in 3.0. Odd indeed. I'm working on a reduction test here to try to figure out exactly what's going on, and what the most minimal code is possible to re-create it. At the moment I can say it happens much more frequently if I use back and forward buttons, rather then just hitting refresh constantly (although that does it also).
I'll continue to poke at this. It may be related to an external CSS file, at least that seems to be a link at the moment. I hope to isolate it down further.
