Autsch!
Das id="kontakt" im form-Tag war zuviel, also:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<style type="text/css">
#kontakt
{ display: block;
width: 100px; height: 25px;
background: url(knorm.jpg) no-repeat;
}
#kontakt:hover
{
background: url(khover.jpg) no-repeat;
}
img
{ border: none;
}
</style>
</head>
<body>
<form action="http://www.example.test/bin/k.pl" method="post">
<input type="image" id="kontakt" src="knorm.jpg">
<input type="hidden" name="p1" value="e">
</form>
</body>
</html>