If you are utilizing a custom masterpage it is very common to use the visible="false" tag to hide element SharePoint is looking for but you don't want displayed on your page.  If you did this with the <strong>PlaceHolderPageTitleInTitleArea </strong>tag at first glance everything works as it should.  However, you will notice that you can no longer save pages through the UI without getting the "You must specify a value for this required field" error. 

Here is how to bypass this issue.  Create a css class and call it .hideplaceholder (or whatever you like) to look like this...

.hideplaceholder {

visibility: hidden;

}

Then wrap your <strong>PlaceHolderPageTitleInTitleArea </strong>in a &lt;asp:Panel&gt; tag that looks like this...

&lt;asp:panel runat="server" cssclass="hideplaceholder"&gt;
  &lt;asp:contentplaceholder id="PlaceHolderPageTitleInTitleArea" runat="server" /&gt;
&lt;/asp:panel&gt;

This will successfully hide the panel and allow updates to pages on the site.  For more effected tags reference the MSDN article <a href="http://blogs.msdn.com/b/tmathis/archive/2010/03/18/you-must-specify-a-value-for-this-required-field-error-when-hidding-placeholderpagetitleintitlearea.aspx" target="_blank">here</a>.