Looks like jason put some hidden tags OUTSIDE the form tag:
<input type="hidden" name="do" value="search_results">
<input type="hidden" name="search_forum" value="all">
<form method="get" action="gforum.cgi">
<input type="hidden" name="do" value="search_results">
<input type="hidden" name="search_forum" value="all">
<form method="get" action="gforum.cgi">