I have a question on MasterPages?

[Learner]

Hello,
I have one MasterPage (it has Header and Side lay out on it) and it
has 3 component placeholders. Out of which the side one for the links
to navigate through the site, the Header place is for to display the
loginstatus and couple of links and and finally the content pages
display in the content area of the MasterPage.

Now, I have around 10 component pages and all most of all of the pages
have the same content to display in the Header area of the MasterPage
except couple for couple content pages. Theer may be a way to have
control over these links to hide when these two content pages appear in
the conten area. But with my experience I just tried to customize the
Header of the MasterPage through these two content pages and its
throwing me an error when I navigate through these pages.

here is the contentplace holder of the MasterPage in one of the two
content pages I am trying to use

------------------**************** this code snippet is from
contactus.aspx**********************
<asp:Content ID="Content3" ContentPlaceHolderID="ContentPlaceHolder1"
Runat="Server">

<table width="100%" cellpadding="0" cellspacing="0">
<tr>
<td align="left" width="50%"
class="LoginInfo">
<asp:LoginName ID="LoginName2"
runat="server" FormatString="You are logged in as

<b>{0}</b>"/>
<asp:Label ID="_lblDN" runat="server"></asp:Label></td>
<td align="right" width="50%"
class="LoginInfo">
<asp:LoginStatus ID="LoginStatus1"
runat="server" />
</td>
</tr>
</table>


</asp:Content>
************************************End of the code from
contactus.aspx*************************************************


As you see _lblDN is not being recognised when I navigate through
these two pages and I dont' have any problem with this label control
that is physically sitting on the MasterPage in the Header portion.

Coule some one help me understand how to hide these links just for
these two pages?

Please bear with my explanation and hope its understandable or else let
me know and I can try explaning it better.

Thanks in advance.
-L