_coll_search_form.widget.php line 92:
echo '<input type="submit" name="submit" class="submit" value="'.T_('Search').'" class="search_submit" />';
Replace with
echo '<input type="submit" name="submit" value="'.T_('Search').'" class="search_submit" />';
Committed to CVS HEAD on 2008/04/30
This was the first bug I found directly after release of 2.4.2