以下原代码ＩＥ下调试一切正常，Opera下调试可以起作用，但会打乱布局，而火狐下根本就不起作用，不知道为何，请达人赐教！！
-----------------------------------------------源代码如下----------------------------------------------------
<script language = "JavaScript ">
function selectusertype()
{
if(document.regform.usertype[0].checked==1){
selectusertypeqy1.style.display= 'none ';
selectusertypeqy2.style.display= 'none ';
selectusertypeqy3.style.display= 'none ';
selectusertypegr1.style.display= 'block ';
selectusertypegr2.style.display= 'block ';
}
else
{
selectusertypeqy1.style.display= 'block ';
selectusertypeqy2.style.display= 'block ';
selectusertypeqy3.style.display= 'block ';
selectusertypegr1.style.display= 'none ';
selectusertypegr2.style.display= 'none ';
}
}
//--
</script>
<form name= "regform " method= "post " action= "reg.asp " onsubmit= "return checkaddpro() ">
<div id= "formwrapper ">
<FIELDSET>
<LEGEND> 用户名及类型 </LEGEND>
<br />
<table width= "600 " border= "0 " align= "center " cellpadding= "0 " cellspacing= "0 ">
<tr>
<td width= "100 " height= "24 " align= "right "> <span style= "color: #666666 "> 用户类型： </span> </td>
<td width= "200 "> <input name= "usertype " type= "radio " value= "1 " checked= "checked " onClick= "selectusertype() " />
<span style= "color: #1e7ace "> 个人用户 </span>
<input type= "radio " name= "usertype " value= "2 " onClick= "selectusertype() " />
<span style= "color: #1e7ace "> 企业用户 </span> </td>
<td> <span style= "color: #666666 "> 请选择您的用户类型。 </span> </td>
</tr>
</table>
<br />
</FIELDSET> <br />
<FIELDSET>
<LEGEND> 基本资料 </LEGEND>
<br />
<table width= "600 " border= "0 " align= "center " cellpadding= "0 " cellspacing= "0 ">
<tr id= "selectusertypegr1 ">
<td width= "100 " height= "24 " align= "right "> <span style= "color: #666666 "> E-mail： </span> </td>
<td width= "200 "> <input type= "text " name= "email " id= "email " size= "25 " maxlength= "30 " /> </td>
<td width= "300 " align= "left "> <div id= "d_email " style= "color: #666666 "> 请输入您常用的电子邮箱地址。 </div> </td>
</tr>
<tr id= "selectusertypegr2 ">
<td width= "100 " height= "24 " align= "right "> <span style= "color: #666666 "> 真实姓名： </span> </td>