I also get some exceptions when I look at a page - change its source then refresh it.. but only on the first time.
Did you try to refresh a second time? Or maybe it helps just going to the address bar of your browser and pressing enter twice.
Okay. I tried that and in IE I do see the same pattern as you...
It works after a refresh (although sometimes I have to clear the browser cache for it to come up)
Not so successful in Firefox and definitely not working for me using the browser inside Eclipse. (Does anyone know how to clear that one's cache?)