my layer is stupid in mozilla firefox when i change its position

hi all.
i have a problem with layers in firefox. when i change the position of my layer and move it with an interval (timer) to another position, all content of it will be stretch.
here my script:

function upload(){

document.getElementById('uploaddiv').style.top = 10;
document.getElementById('uploaddiv').style.left = 255;
document.getElementById('uploaddiv').style.visibility = "visible";
goforview();
}

function goforview(){
ii=120;
interval2 = setInterval(dynamic2,100);
}
function dynamic2(){
if (ii<=300){
ii +=10;

document.getElementById('uploaddiv').style.top = ii;
}else{
clearInterval(interval2);
}
}
upload();





i call upload function by a link
only firefox has that problem.

somebody help me plz

 

??? what can i do ???

 

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