A user has had this happen two times today, not sure why it's occurring.  They use SO-A to enter a sales order, and when they tab off the "Ready to invoice" field to go to the line items screen, instead of opening the line items it prompts "Use default ending lines" and then says there are no billable items do you wish to close the SO?  The SO shows up in the SO listing as #0. You can't edit the SO w/o the same issue occurring so we end up starting a new SO.  Happened with two different customers.
 
One thing I did notice with the two SO's - in the Ship To field, there is the phrase "Has deposits".
This does not show on ones that were entered successfully. In looking at the customer records, this phrase does not show up in any of the notes, and neither customer is showing to have a deposit balance.  On customer is on credit hold, one is not.
 
Anyone seen this issue before?  It's baffling.