If document.getElementById() isn’t returning the results in IE that you expect, checkand see if you have any form fields with that name. It seems like IE returns them from getElementById() – even if you manually give them an ID different from the name, that doesn’t conflict! Your only hope seems to be renaming the element you need to select, so that it doesn’t have the same name as any of your form fields.
This is a known bug in IE6, IE7, and IE8 (when not in Standards mode)
http://webbugtrack.blogspot.com/2007/08/bug-152-getelementbyid-returns.html
IE pulls their matches from the static document.all collection which causes serious conflict issues. There is a workaround built into the jQuery library or you can use the one posted on the bug tracking site above.
thanks, maven