去掉这三段代码就行了,试试

IF Trim(Request.Form("Verifycode"))<>Trim(Session("Verifycode")) then
   Call KS.Alert("登录失败:\n\n验证码有误，请重新输入！","Login.asp")
   exit Sub
  end if

-------------------------------------------------

<tr>
            <td align="right">验证码：</td>
            <td height="30"><input type=text name="Verifycode" maxLength=6 size="6" tabindex="3" class="textbox">
              <-请在验证码框输入 <IMG style="cursor:hand;" src="../KS_Inc/verifycode.asp?n=<%=Timer%>" onClick="this.src='../ks_inc/verifycode.asp?n='+ Math.random();" align="absmiddle">&nbsp;</td>
          </tr>

--------------------------------------------------

if (ObjForm.Verifycode.value == '') {
    alert ('请输入验证码！');
    ObjForm.Verifycode.focus();
    return false;
  }