My site runs on 4.3.4.  There are 2 portals with about 600 pages, and it's very active site. I've had the SearchEngineScheduler run once a day,
and this is the first time in a year that I got this scheduler exception (for 3 days continuously) (see below).
Will someone please tell me what activities would cause this deadlock, and what I should do to prevent it?
Also, in the schedule menu, how do I set a specific time for the search engine to run?

InnerException: Transaction (Process ID 66) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction.
FileName:
FileLineNumber: -1
FileColumnNumber: -1
Method:
StackTrace:
Message: System.Data.SqlClient.SqlException: Transaction (Process ID 66) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction. at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection) 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.SqlDataReader.HasMoreRows() at System.Data.SqlClient.SqlDataReader.ReadInternal(Boolean setTimeout) at System.Data.SqlClient.SqlDataReader.Read() at DotNetNuke.Common.Utilities.CBO.FillCollection(IDataReader dr, Type objType) at DotNetNuke.Services.Search.SearchDataStore.GetSearchItems(Int32 ModuleId) at DotNetNuke.Services.Search.SearchDataStore.StoreSearchItems(SearchItemInfoCollection SearchItems) at DotNetNuke.Services.Search.SearchEngineScheduler.DoWork()

4.3.4 is a pretty old and not the most stable version, I suggest to upgrade at least to 4.3.7, though 4.4.1 has a number of performance improvements, while 4.5.5, 4.6.2 and 4.7.0 provide a number of nice new features (and bugs corrected).