code:
<a href="msn.html" onmouseover="image4.src='images/msn-over.png';"
onmouseout="image4.src='images/msn.png';">
<img name="image4" src="images/msn.png" border=0></a>
</div>
You had the ; inside the single quotes. Which ment it was looking for images/msn.png;