I have had a few instances where certain pages would hang randomly. Using the latest firefox when it happened but the problem also seemed to happen in IE8 as well.
It will hang and then recover then hang and recover again over and over until I close the browser and reopen it. But going back to the page will cause it again until I restart. After that it's fine again for a while. Seems pretty random though and it has only happened to me a couple of times so far.