SQLSRV Problems in 2.5.13
From Joomla! Documentation
The "J2.5" namespace is a namespace scheduled to be archived. This page contains information for a Joomla! version which is no longer supported. It exists only as a historical reference, it will not be improved and its content may be incomplete and/or contain broken links.
The main article and category list queries are broken for SqlSrv based sites.
To fix please apply the [hotfix that is available on http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=31634].