As Ben said, make sure you have an id on the form tag. Make sure you do not have a submit button named submit on the form. That causes issues since it overrides the method submit on the form.
ALSO IE does not set the name attribute, so you may run into issues reading it on the server. Take a look at the code here:
http://www.pascarello.com/examples/createElement.html which shows you how to get around that quirk. It might be easier to just add the hidden element to the form and reference it and set the value.
Eric