Iceland - that's odd, because I see *nothing* like this when the site loads. Just the site - nothing else. Maybe it's because I'm using Mozilla - I dunno.
I don't know *for sure* what it could be. But I've seen odd characters appear in IE6 like this when there's comments in the code. You know, like
<!-- end of div --> kind of stuff. IE6 has this weird bug - I can't remember what triggers it, but if you just use comments like this, it'll show...how do I explain this? LOL. It'll show the last number of characters in the page that's equal to how many comments are in the page. So, if you have 4 commented fields in the whole page, then the last 4 characters in the page will appear.
It's really bizarre. But I've seen it *rarely* - and the stuff usually shows up at the bottom of the page, not the top. And unless the last few characters of your page are "51", then this bug wouldn't be the issue.
I'd agree though - check out the plugins and see if shutting some off help out. Otherwise (unless by fluke, my thoughts are right, because I *do* know how to get around that bug) I don't have much assistance to offer.