Sorry, I don't think there's a solution other than not issuing the credit note until the client pays the invoice (not that I'm suggesting this). It does all even out in the end though.

With a really complicated Crystal report (that might not even be do-able), it might be possible to exclude credit notes except for those that have been applied to fully paid invoices. That's pretty complicated linking though. Fortunately, SalesAnalysis has enough information to allow you to link back into the AR transaction file. The client would also need to be careful about moving transactions to history so that you would know which file it would be in.