ok, here's the problem, you're telling the validator that you're closing the form tag when you use this code:
<form method="get" action="searchmembers.php" />
change to this:
<form method="get" action="searchmembers.php">
and you'll be fine.
One thing you may consider so the page will look ok in Mac IE is to push those form tags to outside the <table> </table> they're in - you've got them kinda randomly inside some td tags - Mac IE doesn't usually handle that well.
