On April 12th, I installed all available patches in the order they were released.
 
Since then, we randomly get These messages when we post invoices.
 
This morning, I looked over the shoulder of the accountant while she processed and posted invoices.
We checked all deposits and they were linked to the correct Sales orders.  We also got the warning
that the invoice had already been printed with this deposit on it (    )
 
When we posted the invoices, we got 2 of the above referenced messages.
 
One thing I noticed is that the date in the title bar was 10-19-05, but, while
invoices were being posted, it showed a date of 3-20-07.
 
What do these messages mean?  Is there something I can check?

1. These Orders are converted from EDI orders.
2. The order is released by using SO-A, setting RTI on the header to Y, Pressing F10 and then selecting N for all three document options.
3. No packing slip is printed
4. We authorize a CC, enter a deposit into AR-N and tie it to the SO
5. An Invoice is then printed using the PRINT button in SO-A
6. We answer 'N' to 'Use Ship Date as Invoice date' and we use today in both the following date fields.
7. The invoice is then printed and it shows the deposit amount
8. That same day, the order is shipped and a copy of the invoice goes to accounting.
9. After all the packing lists have been processed, all invoices (the new ones from packing lists and the ones printed before) are posted.
10. During this posting process, we get the messages I was referring too before on some of the orders with deposits.
 
From your previous description, I'm not sure if that is our problem or not.  You said that if we answered 'Y' to Use ship date as Invoice date, this could be a problem, but we are answering 'N' to this question.