what is the massaging dispatch in dnn schedule?

all of my site massaging dispatch has bellow error. 

i see this errors in schedule page and schedule reports. 

Messaging Dispatch Messaging Scheduler DoWork Starting 75a75541-6068-4354-871a-b37300d8d898 Messaging Scheduler Failed: System.Data.SqlClient.SqlException (0x80131904): Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression. The statement has been terminated. at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose) at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady) at System.Data.SqlClient.SqlDataReader.TrySetMetaData(_SqlMetaDataSet metaData, Boolean moreInfo) at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady) at System.Data.SqlClient.SqlDataReader.TryConsumeMetaData() at System.Data.SqlClient.SqlDataReader.get_MetaData() at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async, Int32 timeout, Task& task, Boolean asyncWrite, SqlDataReader ds) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, TaskCompletionSource`1 completion, Int32 timeout, Task& task, Boolean asyncWrite) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method) at System.Data.SqlClient.SqlCommand.ExecuteReader(CommandBehavior behavior, String method) at System.Data.SqlClient.SqlCommand.ExecuteDbDataReader(CommandBehavior behavior) at System.Data.Common.DbCommand.System.Data.IDbCommand.ExecuteReader(CommandBehavior behavior) at DotNetNuke.Data.PetaPoco.PetaPocoExt.ExecuteReader(Database database, String sql, Object[] args) at DotNetNuke.Data.PetaPoco.PetaPocoHelper.ExecuteReader(String connectionString, CommandType type, String sql, Object[] args) at DotNetNuke.Services.Social.Messaging.Data.DataService.GetNextMessagesForInstantDispatch(Guid schedulerInstance, Int32 batchSize) at DotNetNuke.Services.Social.Messaging.Internal.InternalMessagingControllerImpl.GetNextMessagesForInstantDispatch(Guid schedulerInstance, Int32 batchSize) at DotNetNuke.Services.Social.Messaging.Scheduler.CoreMessagingScheduler.HandleInstantMessages(Guid schedulerInstance) at DotNetNuke.Services.Social.Messaging.Scheduler.CoreMessagingScheduler.DoWork() ClientConnectionId:8d32108f-5d38-4437-9b82-af5edde83ebf

and this error cause my ScheduleHistory table size grow so fast. 

can i desable this schedule?

please help to figure out and solve this problem?