CMS Made Simple is a wonderfull open source CMS with load upon loads of different modules with amazing functionality. Unfortunately most of these projects are under constant development which mean that the developer rarely gets to implement a fully functional documentation. This I experienced with a client project where my company implemented a front end user login system using FrontEndUser (FEU) module for CMSMS. The admin interface is very complex and it's functionality is very poorly described in the FAQ. When the users and user groups were created a login box was easily customized for the system but when users were logged in, the protected content was never showed. The solution is as follows:

{cms_module module=frontenduser form=silent}
{if $customcontent_loggedin}
  {content}
{else}
  {global_content name='unauthorized'}
{/if}

The point is to use the form=silent parameter in the module call. That way information about the login process is related to the display of protected information. EDIT: The solution above wasn't all that stable. I had a look at the CustomContent module instead. and used the syntax:

{if $ccuser->loggedin()}
  {content}
{else}
  {errorbox}
{/if}