IE shows “error on page” when making change on the drop down menu

I am using drop-down menu in my web site. Basically, when clicking different items in the drop-down menu, the different images should be displayed. It works perfectly in the firefox (no single error in the control panel of the firefox). But it does not work in the internet explore 6 or 7, basically, it shows “error on page” in the left bottom corner. I have read some previous threads on this topic, and they wont help. Any clues ? I really appreciate !