Ho utilizzato questo codice per uno scroll div e fino all'ultimo aggiornamento di FF è sempre andato.
Ora funziona solo con IE.
Codice PHP:
<script type="text/javascript"><!--//
var ourInterval;
var origColor = "#000000";
var overColor = "#000000";
var scrollSpeed = 50;
var scrollHeight = 5;
function scrollStart(direction, divID, elementID){
//CHANGE THE BACKGROUND COLOR OF THE TD THE MOUSE IS OVER
document.getElementById(elementID).style.backgroundColor = overColor;
// REPEATED CALL EITHER scrollUp OR scrollDown
ourInterval = setInterval("scroll"+direction+"('"+divID+"')", scrollSpeed);
}
function scrollEnd(which){
// OUR MOUSE IS OUT, SO RETURN TD TO ORIGINAL COLOR
document.getElementById(which).style.backgroundColor = origColor;
// STOP CALLING THE SCROLL FUNCTION
clearInterval(ourInterval);
}

function scrollUp(which){
// SET THE SCROLL TOP
document.getElementById(which).scrollTop = document.getElementById(which).scrollTop - scrollHeight;
}
function scrollDown(which){
// SET THE SCROLL TOP
document.getElementById(which).scrollTop = document.getElementById(which).scrollTop + scrollHeight;
}
//--></script>
</head>

<body>
<table width="300" border="0" cellspacing="1" cellpadding="0" bgcolor="#ffffff">
<tr>
<td bgcolor="#F3F9F1" width="100%" id="peopleUp" onMouseOver="scrollStart('Up', 'people', 'peopleUp');" onMouseOut="scrollEnd('peopleUp');">
[img]images/down.jpg[/img]
</td>
</tr>
<tr>
<td>
    <div id="people" style="height:100px; overflow-y:hidden; overflow-x:hidden;">
  elenco lungo........
    </div>
</td>
</tr>
<tr>
<td bgcolor="#F3F9F1" id="peopleDown" onMouseOver="scrollStart('Down', 'people', 'peopleDown');" onMouseOut="scrollEnd('peopleDown');">
[img]images/up.jpg[/img]
</td>
</tr>
</table> 
Sapete dirmi cosa non lo rende compatibile? FireBugs non da nessun errore