I recently attached the Database.mdf located in app_data in Microsoft SQL Server Management Studio. DNN website will not load now! I receive the following error.

Cannot open user default database. Login failed.
Login failed for user 'NT AUTHORITY\NETWORK SERVICE'.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Data.SqlClient.SqlException: Cannot open user default database. Login failed.
Login failed for user 'NT AUTHORITY\NETWORK SERVICE'.

Source Error:
An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[SqlException (0x80131904): Cannot open user default database. Login failed.
Login failed for user 'NT AUTHORITY\NETWORK SERVICE'.]
   System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) +435
   System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) +82
   System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) +105
   System.Data.SqlClient.SqlConnection.Open() +111
   Microsoft.ApplicationBlocks.Data.SqlHelperParameterCache.DiscoverSpParameterSet(SqlConnection connection, String spName, Boolean includeReturnValueParameter, Object[] parameterValues) +204
   Microsoft.ApplicationBlocks.Data.SqlHelperParameterCache.GetSpParameterSetInternal(SqlConnection connection, String spName, Boolean includeReturnValueParameter) +303
   Microsoft.ApplicationBlocks.Data.SqlHelperParameterCache.GetSpParameterSet(String connectionString, String spName, Boolean includeReturnValueParameter) +154
   Microsoft.ApplicationBlocks.Data.SqlHelperParameterCache.GetSpParameterSet(String connectionString, String spName) +36
   Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteReader(String connectionString, String spName, Object[] parameterValues) +200
   DotNetNuke.Services.Log.EventLog.DBLoggingProvider.Data.SqlDataProvider.GetLogTypeConfigInfo() +68
   DotNetNuke.Services.Log.EventLog.DBLoggingProvider.DBLoggingProvider.GetLogTypeConfigInfo() +108
   DotNetNuke.Services.Log.EventLog.DBLoggingProvider.DBLoggingProvider.GetLogTypeConfigInfoByKey(String LogTypeKey, String LogTypePortalID) +61
   DotNetNuke.Services.Log.EventLog.DBLoggingProvider.DBLoggingProvider.AddLog(LogInfo objLogInfo) +72
   DotNetNuke.Services.Log.EventLog.LogController.AddLog(LogInfo objLogInfo) +208
 

I have detached from the management studio, restore the dotnetnuke directory, and rebooted more then once and the website still will not load.

PLEASE HELP!!!

1. How do I fix this?
2. What causes this?
3. Is there a way to be connected to the management studio and web at the same time. I really need access to the database via ODBC to share information    with another application.

 Thanks in advance!

I am still having a hard time grasping what is going on.

Permissions read network service has full control. So I reset all child objects in the dotnetnuke folder. Tried restarting WWW service and still receive the same error. Linked Database.MDF back up to MSSMS and then the website loads! But only for a little bit and then I receive the same error again!

What SQL server security should the database have?

How fustrating....

Try to reset "read/write" permission on only the MDF File and the log file in the App_Data Folder