function disableImgLoading(evt) {
var i,ib,el,l = document.getElementsByTagName("img");
for(i = 0, ib = l.length; i < ib; i++){
el=l[i];
if(el.className && el.className.match(/file_preview/)){
el.style.backgroundImage="none";
}
}
}

if(window.addEventListener) {
window.addEventListener("load", disableImgLoading, true);
} else if(window.attachEvent) {
window.attachEvent("onload", disableImgLoading, true);
}