paypal and search buttons conflict

correction.. the paypal button is not an iframe, its just a plain form like this:

<form action="https://www.paypal.com/cgi-bin/webscr" method="post" style="text-align:center;margin-top:5px">
<input type="hidden" name="cmd" value="_s-xclick">
<input type="hidden" name="hosted_button_id" value="xxxxxxxxxxxxxxxx">
<input type="image" src="https://www.paypalobjects.com/en_US/i/btn/btn_donateCC_LG.gif"
border="0" name="submit" alt="Donate to Equity Trust by Paypal">
<img alt="credit cards" border="0" src="https://www.paypalobjects.com/en_US/i/scr/pixel.gif" width="1"  height="1">

I found a solution, if anyone has a similar problem. I installed the plugin Nice Paypal Button Lite (I’ll suggest to the client he upgrade to the full version for $15).

Then I enabled shortcodes in textwidgets but adding this line to my functions.php:
add_filter('widget_text', 'do_shortcode');
No more conflict: the search button searches, the paypal button goes to paypal.