After uploading a custom SQL based report in CRM, users see a generic "Reporting Error"

After uploading a custom SQL based report in CRM, users see the following error when trying to run the report:
Reporting Error
The report cannot be displayed. (rsProcessingAborted)

If you review the SSRS report logs, you can see the following error:
processing!ReportServer_0-4!ef0!09/09/2013-13:21:40:: e ERROR: Throwing Microsoft.ReportingServices.ReportProcessing.ReportProcessingException: , Microsoft.ReportingServices.ReportProcessing.ReportProcessingException: Cannot create a connection to data source 'CRM'. ---> System.Data.SqlClient.SqlException: Login failed for user 'NT AUTHORITY\ANONYMOUS LOGON'.
   at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
   at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj)
   at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj)
   at System.Data.SqlClient.SqlInternalConnectionTds.CompleteLogin(Boolean enlistOK)
   at System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, Boolean ignoreSniOpenTimeout, Int64 timerExpire, SqlConnection owningObject)
   at System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(String host, String newPassword, Boolean redirectedUserInstance, SqlConnection owningObject, SqlConnectionString connectionOptions, Int64 timerStart)
   at System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(SqlConnection owningObject, SqlConnectionString connectionOptions, String newPassword, Boolean redirectedUserInstance)
   at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, Object providerInfo, String newPassword, SqlConnection owningObject, Boolean redirectedUserInstance)
   at System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection)
   at System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnection owningConnection, DbConnectionPool pool, DbConnectionOptions options)
   at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject)
   at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject)
   at System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject)
   at System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection)
   at System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory)
   at System.Data.SqlClient.SqlConnection.Open()
   at Microsoft.ReportingServices.DataExtensions.ConnectionExtension.Open()
   at Microsoft.ReportingServices.DataExtensions.SqlConnectionWrapperBase.Open()
   at Microsoft.ReportingServices.Diagnostics.DataExtensionConnectionBase.OpenDataSourceExtensionConnection(IProcessingDataSource dataSourceObj, String connectString, DataSourceInfo dataSourceInfo, String datasetName)
   --- End of inner exception stack trace ---;


Additional errors you may not be exactly the same but similar to those above. The key data to look for is in the stack trace for the following items:

Stack contains:
at Microsoft.ReportingServices.Diagnostics.DataExtensionConnectionBase.OpenDataSourceExtensionConnection

Error contains:
Microsoft.ReportingServices.ReportProcessing.ReportProcessingException: Cannot create a connection to data source 'CRM'. ---> System.Data.SqlClient.SqlException:


NOTE: SSRS default log location is: DRIVE:\Program Files\Microsoft SQL Server\MSRS10_50.MSSQLSERVER\Reporting Services\LogFiles