Muchas gracias, haciendo lo que me comentas:
Código HTML:
....
<!-- INCLUDE masthead.html -->
{include file=masthead.html}</div>
<!-- End Masthead -->
<!-- Begin Page Content -->
<div id="page_content">
<!-- Begin Sidebar -->
<div id="sidebar">
<!-- INCLUDE sidebar.tpl -->
{include file=login.tpl}
{include file=sidebar.tpl}
</div>
.........
me funciona genial
