I've seen this before, though not the solution because this issue makes permanent changes to your costing data once Day End is run.

Though I was never able to figure out what caused this I suspect that getting my client onto the current versions went a long ways towards preventing it from happening again.

We just opened an office in Winnipeg, give me a call if I can assist you in any way. My Winnipeg number is(204) 944-0302.