Need Help Debugging Script/Error in Script - IE7 vs FF: <Option> tags truncated

I'm trying to inject a set of <option> clauses into a <select>. The clauses are built from a page scrap done while this page is loading.
I've loaded prototype.js, scriptaculous.js, and prototype/main.js

What I've coded for the Select is:

<select name='emailNames' id='emailNames' size='4' onChange='sOnChange();'></select>

My <select> box is blank in IE7 (this works fine in FF). What I see in the IE7 debugger (ieinspector's dominspector) is:

<SELECT id=emailNames onchange=sOnChange(); size=4 name=emailNames _extended="true">No contact (1)</OPTION><OPTION>No Contact (2)</OPTION>...

Hum, very different. My research into the '_extended="true"'
has been inconclusive. Too new at this to understand all that the element.extend discussions are about. Is this a problem for my application?

But the wierdest part is the 1st <option> clause has the tag truncated.

Code to produce and inject the clauses is:

var a = new String();
for (var i in emailTemplates) {
a += "<option>" + i + "</option>";
}
//$('emailNames').extend = Prototype.K;
//$('emailNames').innerHTML = a;
$('emailNames').update(a);
//document.forms.form1.emailNames.innerHTML = a;
//$('emailText').update(c);
// var d = $('emailText');
//d.update(a);

Can anyone tell me what is going on? Some direction to go to fix this? I'm very new to jscript and OO in general but have been coding a long time. TIA!

Alright, I have a satisfactory workaround. In the base HTML, I wcoded a <div> in place of the <select>:

<div id='emailN'> </div>
<!--select name='emailNames' id='emailNames' size='4' onChange='sOnChange();'>
<option>...select a template...</option>
</select-->

In the js, I coded the complete <select> statement:

var a = new String();
a = "<select name='emailNames' id='emailNames' size='4' onChange='sOnChange();'>";
for (var i in emailTemplates) {
a += "<option>" + i + "</option>";
}
a += "</select>";
$('emailN').update(a);

This is working in both IE7 and FF. I am new to the worlds of OO and javascript and don't know how/why this works. I would appreciate an explaination.