since I log the JS errors on my site, I found a lot generate by the wordpress stat Plugin. I got the error only with IE 7, it says (I have to translate it, because I got the message in german)
no object in line xxx (it depends on the length of the site since the IE is not able to say the right line of an JS error).
So I did take a look at the JS Code which is included in my site from the plugin. but there's no error.
MY guess is, the problem is that you send the JS Code in iso-8859-1 but my site is in utf-8, this is a problem for the IE sometimes.
Another small and not important prob is this:
JS is case sensitive, the handler is called onload.