Problem with a html code

Hi everybody! Well, I´ve got a problem with firefox in my forum:
http://probamosmucho.foroactivo.com/
In theory, the announcement would looks like this:

Spoiler:

but looks cut:

Spoiler:

I used that code

Code:

<script type="text/javascript">
<!--


var rollOverArr=new Array();
function setrollover(OverImgSrc,pageImageName)
{
if (! document.images)return;
if (pageImageName == null)
    pageImageName = document.images[document.images.length-1].name;
rollOverArr[pageImageName]=new Object;
rollOverArr[pageImageName].overImg = new Image;
rollOverArr[pageImageName].overImg.src=OverImgSrc;
}

function rollover(pageImageName)
{
if (! document.images)return;
if (! rollOverArr[pageImageName])return;
if (! rollOverArr[pageImageName].outImg)
    {
    rollOverArr[pageImageName].outImg = new Image;
    rollOverArr[pageImageName].outImg.src = document.images[pageImageName].src;
    }
document.images[pageImageName].src=rollOverArr[pageImageName].overImg.src;
}

function rollout(pageImageName)
{
if (! document.images)return;
if (! rollOverArr[pageImageName])return;
document.images[pageImageName].src=rollOverArr[pageImageName].outImg.src;
}
//-->
</script>
<a href="http://www.youtube.com/watch?v=8eMtEDuIZUU/" onmouseover="rollover('Humanos')" onmouseout="rollout('Humanos')"><img src="http://i261.photobucket.com/albums/ii42/Nina_Luchia/1-1.png" name="Humanos" alt="Humanos" border="0"></a><script type="text/javascript"><!--
setrollover("http://i261.photobucket.com/albums/ii42/Nina_Luchia/15.png");//--></script><img name="a10" src="http://i261.photobucket.com/albums/ii42/Nina_Luchia/2-1.png" width="345" height="300" border="0" usemap="#CuadroAnuncio" alt="Pulsa los textos"><map name="CuadroAnuncio"><area shape="rect" coords="22,146,340,179" href="http://www.youtube.com/watch?v=8eMtEDuIZUU" alt="Predeterminados"><area shape="rect" coords="43,193,188,227" href="http://www.youtube.com/watch?v=8eMtEDuIZUU" alt="Registros"><area shape="rect" coords="203,183,310,253" href="http://www.youtube.com/watch?v=8eMtEDuIZUU" alt="Misterio gélido"></map><a href="http://www.youtube.com/watch?v=8eMtEDuIZUU" onmouseover="rollover('Mutantes')" onmouseout="rollout('Mutantes')"><img src="http://i168.photobucket.com/albums/u185/The_Best_Black/Graficos/3-2.png" name="Mutantes" alt="Mutantes" border="0"></a><script type="text/javascript"><!--
setrollover("http://i261.photobucket.com/albums/ii42/Nina_Luchia/imsingingoah.png");//--></script>

Help please!

up!