Problem swapping image in IE with relative url

[Hubbers]

I have this function for deselecting a groupd of links and images and
highlighting another. Basically I want to make all the lines to be
grey (#999) except the one that is clicked which should be red (#c03)
at the same time a folder image is opened or closed depending which
line is clicked. It works fine in FireFox but not in IE6.

function doFolder(x) {
// alert(x);
for (n=1;n<4;n++) {
document.getElementById('img' + n).src = 'img/IconCloseFolder.gif';
document.getElementById('link' + n).style.color = '#999';
}
document.getElementById('img' + x).src = 'img/IconOpenFolder.gif';
document.getElementById('link' + x).style.color = '#c03';
}

It works on these three lines of code:

<p><span><img src="img/IconCloseFolder.gif" id="img1" height="12"
width="19" alt="" title="" /><a href="javascript:void(0);" id="link1"
onclick="javascript:doFolder('1');">My Saved Searches</a></span><img
src="img/IconEdit.gif" height="15" width="15" alt="Edit" title=""
/><img src="img/IconDelete.gif" height="15" width="15" alt="Delete"
title="" /></p>

<p><span><img src="img/IconCloseFolder.gif" id="img2" height="12"
width="19" alt="" title="" /><a href="javascript:void(0);" id="link2"
onclick="javascript:doFolder('2');">Orion Project</a></span><img
src="img/IconEdit.gif" height="15" width="15" alt="Edit" title=""
/><img src="img/IconDelete.gif" height="15" width="15" alt="Delete"
title="" /></p>

<p><span><img src="img/IconCloseFolder.gif" id="img3" height="12"
width="19" alt="" title="" /><a href="javascript:void(0);" id="link3"
onclick="javascript:doFolder('3');">Bob's Searches</a></span><img
src="img/IconEdit.gif" height="15" width="15" alt="Edit" title=""
/><img src="img/IconDelete.gif" height="15" width="15" alt="Delete"
title="" /></p>