Periodic Activities - Inventory

I am having difficulty running the Adjust item - Cost entries periodic activity in the inventory menu. It keeps on coming back and telling me that Item application entries cannot be located for specific Item ledger entry numbers. Please can someone assist me in letting me know what entries should be in that item application entry table and what entries should not. I did an experiment in Cronus and deleted half of the records in that table and then ran the Adjust item - Cost entries again and it ran perfectly so now i am really confused. We have implemented the system unsing standard cost only and also need to know how often should this activity be run and also are there other inventory periodic activities that should be run with the one mentioned above - Thank you