I have set up a preload script for an image rotataton on a page. The rotation is pretty fast but it seems to preload them OK.

The problem is that, in IE on certain pages, even after the images have been cahced, switching between images causes the cursor to briefly turn in to eggtimer. Occasionally you can very briefly see the 'downloading from...' in the status bar as it fetches the image.

i don't understand whats going wrong, but on some machines, it apparrently goes completely nuts and stops them doing anything. It also seems to delay showing the progress bar when you click on a submit button.
Code:
<head>
<script>
function preload_storefronts()
{

    if (document.images)
        {
    storeimg_url = new Array();
    var store_preload_image_object = new Array();
    <!--
    storeimg_url[1] = "../images/boxes/airfresh.jpg";
storeimg_url[2] = "../images/boxes/waste.png";
storeimg_url[3] = "../images/boxes/washroomproducts.jpg";
storeimg_url[4] = "../images/boxes/gardenfurniture.jpg";
storeimg_url[5] = "../images/boxes/heating.png";
storeimg_url[6] = "../images/boxes/pest-control.jpg";
storeimg_url[7] = "../images/boxes/household.jpg";
storeimg_url[8] = "../images/boxes/homeelectric.png";
storeimg_url[9] = "../images/boxes/catering2.jpg";
<!-- etc ... there are 38 images in all -->

           for(var i in storeimg_url)
           store_preload_image_object[i] = new Image();
             store_preload_image_object[i].src = storeimg_url[i];
    }
}

var storetimer;
storetimer = 1000;



var arrpos = 0;
var pause = false;

function storerotate(){
  
  
  if(pause) return;
  var store = document.getElementById('storerotate');
arrpos++;
if (arrpos >= storeimg_url.length) arrpos = 1;
if (arrpos == 24) arrpos++;
store.src= storeimg_url[arrpos];
//if this store is a coming soon item, remove hyperlink.
//If link has been removed and needs to be added, add it.

window.setTimeout('storerotate();',storetimer);
}


</script>
</head>
<body 
onload="preload_storefronts(); window.setTimeout('storerotate()', storetimer);   "
>
I'm not really sure if IE is loading the images again for every switch, or if its purely the processing that's playing silly buggers with the browser. The images are about 3k each and switching every second.

Any ideas?