'fixed' bg image offset

I have some HTML that looks a bit like this:

<div id="panel">
<div>
<p>blah</p>
</div>
</div>

The relevant CSS looks like this:

div#panel {
position: absolute;
left: 100px; top: 60px; width: 600px; height: 300px;
border:1px solid #0F296E;
background: url(images/line.png) fixed;
overflow: auto;
}

'line.png' is a 1x300 high image.

When I view the page in IE the background image is "tucked" into the top
left corner of the DIV. When I view it with FF the background starts
about 1/3 of the way down the DIV. What do I have to do to get the
background image "tucked" into the the top left corner?

Andrew Poulos