Bizarre comment glitch

I just added a Paypal donation link to my blog, and after several days of no comments I got an email from a friend asking me if she had to pay to comment on the site now. So I checked the comments and sure enough, when you hit the submit button it takes you to the Paypal donation screen.

What I had done was insert the PayPal code at the top of the content section on the index page, thusly:

<div id="content">

<div>Please consider supporting BTC News by making a donation through the link below.<br>
<form action="https://www.paypal.com/cgi-bin/webscr&quot; method="post">
<input type="hidden" name="cmd" value="_s-xclick">
<input type="image" src="https://www.paypal.com/en_US/i/btn/x-click-but21.gif&quot; border="0" name="submit" alt="Make payments with PayPal - it's fast, free and secure!">
<input type="hidden" name="encrypted" value="[my PayPal info]"><br></div>

<?php if ($posts) : foreach ($posts as $post) : start_wp(); ?><?php the_date('','<h2>','</h2>'); ?>

Obviously the PayPal action superceded the comment submission action, but I haven’t the foggiest notion why, or how to get around it so I can still have the donation link at the top of each index page.

Any help?