I get the following error rarely, but usually at about the exact same time when it happens... Before I go beating our dba, can you give me any insight why this would occur? Restarting IIS fixes this.

ERROR 2006-10-06 00:22:34,749 Global Application_Error - System.Web.HttpUnhandledException: Exception of type System.Web.HttpUnhandledException was thrown. ---> System.Exception: An error occured: "Object reference not set to an instance of an object."
Please check the file queries.config in folder cmsdesk/metadata/cms/article.
at Kentico.CMS.MetadataEngine.MetadataProvider.EnsureQueries(String applicationName, String className)
at Kentico.CMS.MetadataEngine.MetadataProvider.GetQuery(String queryName)
at Kentico.CMS.DataEngine.GeneralConnection.RunQuery(String queryName, Object[,] params, String where, String orderBy)
at Kentico.CMS.DataEngine.GeneralConnection.ExecuteQuery(String queryName, Object[,] params, String where, String orderBy)
at Kentico.CMS.TreeEngine.TreeProvider.SelectNodes(String path, TreePathTypeEnum pathType, String className, String where, String orderBy, Int32 maxRelativeLevel, Boolean selectOnlyPublished)
at Kentico.CMS.TreeEngine.TreeProvider.SelectNodes(String path, TreePathTypeEnum pathType, String[] classNames, String where, String orderBy, Int32 maxRelativeLevel, Boolean selectOnlyPublished)
at Kentico.CMS.TreeEngine.TreeProvider.SelectNodes(String path, TreePathTypeEnum pathType, String[] classNames, String where, String orderBy, Int32 maxRelativeLevel)
at Kentico.CMS.TreeEngine.TreeProvider.SelectNodes(String path, TreePathTypeEnum pathType, String[] classNames, String where, String orderBy)