刷新页面 第一次搜索总是进入到“文章”搜索

<DIV class=search>
<form action="search.php?searchsubmit=yes" method="post" target="_blank">
<DIV class=s_title id=right4_menu><A id=right4_menu_1 title=album
onclick=check_form(1)>相册</A> | <A class=on id=right4_menu_2 title=forum
onclick=check_form(2)>帖子</A> | <A id=right4_menu_3 title=user
onclick=check_form(3)>好友</A> | <A id=right4_menu_4 title=blog
onclick=check_form(4)>日志</A> | <A id=right4_menu_5 title=group
onclick=check_form(5)>群组</A> </DIV>
<DL>
  <DT><SPAN><IMG src="chachengji_dzx/search_b2.gif"
  border=0></SPAN> <INPUT id=search_select type=hidden value=portal name=mod>
  <INPUT type=hidden value=fdf0a228 name=formhash> <INPUT type=hidden
  value=title name=srchtype> <INPUT type=hidden value=0 name=srhfid> <INPUT
  id=searchkeywords
  onfocus="if (value =='辰溪在线！搜一搜,您会找到想要的东东！'){value =''}" value=辰溪在线！搜一搜,您会找到想要的东东！ name=srchtxt>
  </DT>
  <DD><INPUT type=image src="chachengji_dzx/search_b1.gif"
  border=0 name=image> </DD></DL></FORM></DIV>


<SCRIPT type=text/javascript>
function check_form(n) {
for(i = 1; i < 6; i ++) {
$('right4_menu_'+i).className = '';
}
$('right4_menu_'+n).className = 'on';
$('search_select').value = $('right4_menu_'+n).title;
if(n == 1) {
$('topsrch').action = 's.php?mod=list&searchsubmit=yes';
} else {
$('topsrch').action = 'search.php?searchsubmit=yes';
}
}
</SCRIPT>
</div>


刷新页面 第一次搜索总是进入到“文章”搜索    必须点一下上面的   帖子 相册 好友 日志 才能正常搜索
请问如上代码要修改哪里才能默认搜索帖子