Microsoft Office SharePoint Server 2007 utilizes the "master page" concept familiar to ASP.NET 2.0 developers -- a big improvement in the latest SharePoint release.  Developers wishing to create a custom look and feel for a SharePoint site will probably first open SharePoint Designer and begin dissecting, changing and discarding parts of the default master page ("default.master"); however, it doesn't take long to discover that this is not a trivial process and that removing the wrong ContentPlaceHolder tags renders some of the default pages inoperable.  This is due to the fact that pages inherting the "default" master page expect certain ContentPlaceHolder tags to be available in the base page.
Microsoft has published a How-To document with a code sample that provides a minimal master page which contains all the basic pieces need to have a functioning site.  While this code snippet is a good start, it appears that MS left out the following ContentPlaceHolders:

<asp:ContentPlaceHolder ID="PlaceHolderBodyRightMargin" runat="server"/>
<asp:ContentPlaceHolder ID="PlaceHolderTitleRightMargin" runat="server"/>

If you experience error messages with the standard SharePoint pages after using the "minimal" template, try adding these placeholders.