Client-side fix:
Tools > Internet Options
> 'Settings' under Temporary Internet files
> Select 'Automatically' > OK
CSS FIX - Insert in your CSS:
html {
filter: expression(document.execCommand("BackgroundImageCache", false, true));
}
Javascript FIX:
<script type="text/javascript">
try {
document.execCommand('BackgroundImageCache', false, true);
}
catch(e) {};
</script>