Error 11 Can anyone shed some light on how to correct?

We have an user that is moving parts around on several bill of materials.  He is consistently receiving this message.  Often after the message is received the items behave oddly, such as not being able to delete or modify.  When we try to delete or modify, we go back into the ticket and they are still there.

Any ideas on how to correct.

Error #11: Record not found or Duplicate key on write
Program JT_WorkTicketParts_Bus.pvc
Line 1896

General Information:
File *memory*
Last Key Value
Last Key Text

Last Channel Opened 31630
Last Channel Accessed 31664

Object Number 100540
Object Method ReorderLines
Object Text JT_WorkTicketParts_Bus

Available Memory -1270050