Since May 2007, I have noticed that the invoice numbers are being duplicated with older invoices. Any ideas how to remedy this problem.

I had this same problem, only mine came after using myob for a few years.

Go to setup, preferences, then sales and warn for duplicate invoice and customer PO. that should do it. If that doesn't work, somthing in there will do it.

Hope that works for you.

Thanks 'cdi' I will give that a try,and let you know if that fixes the problem.

I believe I had that problem once a long time ago when my computer crashed. Prior to that I was allowing auto-save to do the saving. Since then I hit save after every sales entry.