Onmouseover not firing in firefox

Hi. I’ve been working on a project for some time now, and just recently I installed Firefox. Now, part of the site (which works perfectly in IE6/7) doesn’t work in Firefox. Here is part of the code:


<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<title>Meniu de navigare</title>
</head>
<body bgcolor="#000437">
<table width="119" style="position:relative; top:35%">
<a href="pag_start.html" target="continut"><tr><td class="nav_bar" height="24" background="p1.png" valign="center" onmouseover="background='p2.png'" onmouseout="background='p1.png'" onmousedown="background='p3.png'" onmouseup="background='p2.png'">Home</td></tr></a>

blah blah blah

</table>
</body>
</html>

(I didn’t copy all of the code because it’s basically the same all the way down)
The main problem is with the link (Firefox apparently doesn’t recognize table rows as links). The second problem is with the onmouseover/onmouseout etc handlers (absolutely nothing happens).
Any ideas how to solve this? Thanks. Bye.

PS: just in case you need to know, the code is for a nav bar.