Sales order issue

Hello, 

I have been having problems with an order. Item #SLM5025 is the problem child. The system would not allow me to change the line to ship out of 000 from 600. I would get an error message saying that an item code is required, When I open the Sales Order there are 2 lines one with no warehouse information and one with warehouse 000 I would manual re-enter the line item in the Line 1 item, then I would change the item, and delete the line, and after accepting and reopening, the system would add a line for the same item # and put it back into whse 600.  All other items have been invoiced on this order. So I went in to see if I could update it and I think I really messed it up this time. There were 2 line left.. Both item #SLM5025, one in 000 and one in 600.  I tried deleting the line in 600 and leaving the dropship (purchase order already released). After accepting and trying to reopen, it says that the order is in the history file! any suggestions on how we can fix this issue, we can not delete the SO due to other items being invoiced against it.

Thank you

Gary