Recently we've had this happen with a few customers. They've got open invoices and need to pay them. Luckily they decide to do that and send us a check. We go into AR-C to record the payment. It shows an amount in Outstanding. After the information is entered in it then decides that regardless of their outstanding balance they don't actually have open invoices (I beg to differ!) Our only choice at this point is to record the payment as a deposit to the customer's account. We can then enter AR-C again and see that they now have both outstanding credits and debits. Great. Let's apply them together and cancel the two out! NO DICE. When you try it comes up with a blank list of open invoices wanting us to pick one of the nonexistent choices.

Has anyone got any sort of idea as to what is going on with our customer payments? This is pretty annoying.
 
Yes, this is an official *BUMP* message

Does the AR Aging show any open invoices?  What about Aging as of 12/31/2009 or something like that?  If they were posted with an erroneous future date, they will not be on a current aging or available to be paid with a payment dated prior to the invoice date.