follow up.

i fixed by editing tpl_contact_us_default.php with <br class="clearBoth: /> after </label>

<fieldset>
<legend><?php echo CATEGORY_ANTIROBOTREG; ?></legend>
<label class="inputLabel" for="antirobotreg"><?php echo ENTRY_ANTIROBOTREG ?></label>
<br class="clearBoth" />

cheers