Haven't tried/run into the spoiler issue myself so far, but this sort of behavior has been happening to me more and more these days (in both IE8 and Firefox 3.6.x), and yes, I do suspect it has something to do w/ pages not getting fully rendered in a prompt fashion for whatever reasons -- sometimes, I just have to reload the page.
In my case, the behavior is not only limited to being bounced to the top of the page although that particular behavior used to happen to me all the time when the site software was new and I was still using IE6.
_Man_