Environment:
DNN 4.4.1 on 64-bit Win2003 web server
SQL2005 SP2 on a 64-bit dual core Win2003 database server

At times all modules on a page may disappear completely if you installed DNN under a database schema name in SQL2005 (example: databaseOwner=”DNN”).  You can temporarily fix it by clearing the module cache in the site settings (as long as your login module didn’t disappear also!).  When the modules disappear you’ll see an exception in the log that usually states that DNN can’t find vw_ModulePermissions.  This is because the reference to vw_ModulePermissions is not fully qualified in the stored proc GetModulePermission.  SQL Server does it’s best to find the correct schema/owner for the view but it will sporadically fail (possibly only on dual core machines) and default back to “dbo” which will cause the error.  There is also a performance benefit to fully qualifying the database objects because there is a better chance an existing query plan can be reused when the object is fully qualified.

For a permanent fix I changed the following files with the changes below and reinstalled DNN:
DotNetNuke.Data.SqlDataProvider
04.04.00.SqlDataProvider
04.04.01.SqlDataProvider

Find and replace each string making sure to prefix with a SPACE:
“ {objectQualifier}”  to “ {databaseOwner}{objectQualifier}“ 
“ [{objectQualifier}”  to “ {databaseOwner}[{objectQualifier}“ 

Find and replace each string making sure to prefix with a TAB:
“<TAB>{objectQualifier}”   to “<TAB>{databaseOwner}{objectQualifier}“ 
“<TAB>[{objectQualifier}”  to “<TAB>{databaseOwner}[{objectQualifier}“ 

Hope this helps,
Keith Rogers