Js works in FF not IE

[eval(BadCode)]

I should probably know the tricks about javascript not working in IE etc. I'm sure this is something very basic. I just can't figure it out, and it's really not my strong suit.

I'm testing it with IE8.

IE is getting stuck on two of these ajax functions:
--------- the error -----------
Message: Unknown runtime error
Line: 47
Char: 5
Code: 0
------------------------------

function blcode_search(blcode,asa_hash) {
if (window.XMLHttpRequest)
  {// code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  }
else
  {// code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
xmlhttp.onreadystatechange=function()
  {
  if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {
    document.getElementById("results").innerHTML=xmlhttp.responseText;
    }
  }
xmlhttp.open("GET","search/blcode2serial.php?q="+blcode+"&asa_hash="+asa_hash+"",true);
xmlhttp.send();
}

----- These are the two lines that it's complaining about:
document.getElementById("results").innerHTML=xmlhttp.responseText;
document.getElementById("comparison_results").innerHTML=xmlhttp.responseText;


Edit: I tried messing with the security settings and everything... IE is running in please exploit me mode.

[Logic Ali]

It would help to see the all the associated markup, preferably a live URL.
Could the new innerHTML be overwriting something critical?