로그인시 아이디나 패스워드 공백이...

[code]
<table border="0" cellspacing="0" cellpadding="0">
<tr>
<td><table style="margin-left:3px; border="0" cellpadding="0" cellspacing="0">
<tr>
<td height="22" valign="top"></td>
<td valign="top"><input class="outLogin b" name="mb_id" type="text" maxlength="20" required="required" itemname="아이디" onmouseover='chkReset(this.form);' onfocus='chkReset(this.form);' /style="border-width:1px; border-color:rgb(204,204,204); border-style:solid;"></td>
<td valign="top"></td>
</tr>
<tr>
<td></td>
<td id="pw1"><input name="textfield22" type="password" class="outLogin b" /style="border-width:1px; border-color:rgb(204,204,204); border-style:solid;"></td>
<td id="pw2" style="display:none; padding:0px 0px 0px 0px;">
<input class="outLogin b" name="mb_password" type="password" maxlength="20" onmouseover='chkReset(this.form);' onfocus='chkReset(this.form);' /style="border-width:1px; border-color:rgb(204,204,204); border-style:solid;"></td>
</tr>
</table></td>
<td width="65" align="right" valign="bottom"><input name="image2" type="image" onfocus="blur()" src='<?=$outlogin_skin_path?>/img/outLogin_btnLogin.gif' border="0" /></td>
</tr>
</table>
[/code]
이런 로그인 인데요..
평소에 잘되다가 한번씩 "아이디나 패스워드에 공백이 있으면 안됩니다." 가뜹니다.
왜그럴까요?