ERROR 4330

error descr: "The log in this backup set cannot be applied because it is on a recovery path inconsistent with the database."

I noticed a similar post but it had no resolution, here is my situation.

Hardware:
Primary server:
SQL Server 2000 SP3 Enterprise ed (8.00.760)
Win 2003 Server Enterprise ed

Secondary Server:
SQL Server 2000 SP3 Enterprise ed (8.00.760)
Win 2003 Server Std ed


I setup log shipping using the maintenance wizard. Everything is wonderful for 2-3 days until I get an alert from the monitor and the 4330 error shows up ( no structural changes made on the dbs during this period).

My questions are:
1) why?
2) how can I fix it?

I deleted all .trn files copied over to the secondary server and manually re-copied them from the primary server and now the restore job on the seconday server does not fail but does not do anything. I think it does not know which file to load next.

This is the output now:

EXECUTE master.dbo.xp_sqlmaint '-LSRestorePlanID "89D71B4C-4898-45DB-A40E-00D7E1E8D8AF"'



output ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
NULL
Microsoft (R) SQLMaint Utility (Unicode), Version 8.00.760
Copyright (C) Microsoft Corporation, 1995 - 1998
NULL
Logged on to SQL Server 'MISBACKUP'
as 'NERASQLSVR' (trusted)
NULL
NULL
Starting load for plan MIS.diary_logshipping
NULL
Source database - diary
Destination database - diary
Loaded 0 files
NULL
Finished load for plan MIS.diary_logshipping

(15 row(s) affected)