Move your css to an external stylesheet and use conditional commentary to target only the browsers you are having trouble with (I used lower or equal IE7 because I cannot replicate in IE8). I added an addition to the bottom.
Real-time example: http://jsfiddle.net/tw16/Vx9HZ/
Put the conditional comment in <head>as follows:
<head>
</head>
CSS: .
div.messages {
border:0px;
padding:0 0 0;
width:100%;
overflow-x:auto;
background-color:#66C2FF;
}
HTML: .
<td class='messages'>
<div class='messages'>AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
</div>
</td>