In skin/reboot/customer/help/contactus.tpl
You can replace...
Code:
<input type="text" class="maxlength" maxlength="100" id="subject" name="subject" size="32" maxlength="128" value="{if $smarty.get.subject}{$smarty.get.subject}{else}{$userinfo.subject|escape}{/if}" />
With...
Code:
<input type="text" class="maxlength" maxlength="100" id="subject" name="subject" size="32" maxlength="128" value="{$userinfo.subject|escape}" />