ok, now i see what you are talking about...
first thing is related to CSS, not javascript... and all IE/MSN clients will have problems on my site... that is part of our colophon actually:
http://eachparent.com/info/?show=colophon
for the error reported by the browser, i can't investigate more, but i will ask some other guys who can use these browser to check that out... this is strange because that forum is not modified from the original vBulletin... just the style.