Hi.

I see two problems.

First, the <select> box is missing the ID attribute.
IE incorrectly uses the name attribute when an ID tag is missing, which explains why this works in IE.

Also, the <input type="submit"> button should not be used to trigger scripts like that. Unlike the onsubmit event of the <form> element, if the <input> onclick event returns false, as it does in your script, the form could still be submitted.
(IE and Firefox apparently do stop it tho.)

To fix that, try changing the <input type="submit"> to <input type="button"> . That should just trigger the script.