PayPal & Coupon

I had this product for over a year and it seems that it has so many bugs that I seem to find myself using the the free oscommerce product for most of my clients, but I really want to use and I keep thinking maybe it is me.

I have two different stores (different owners, different PayPal Admin account, etc.) that are getting the same message now, when I try to buy something using a small amount 2.99 or 4.99, they are both coming with same error back from paypal.

Transaction Not Completed
We're sorry
Your transaction could not be completed. Either your credit card information or billing address has problems and cannot be processed
Please return to checkout <http://websitename/checkout.php> and try again

keep in mind, I tried using 4 different paypal accounts that I have when testing for clients,

I tried troubleshooting this..

1- I thought maybe PayPal locked my IP, but I had another client try it from their home and THEY got the same message.

2- Keep in mind, the information in the PayPal Admin setting for either of them is correct, since when I click on checkout, I see the owners name and the amount and the detail, etc. and then I log-in the Paypal accounts to use, it shows everything, it is only upon "continue"...

Also I know with the Free OsCommerce, I can do coupon for shipping, but correct me if I am wrong, it does not seem possible from reading your forum that I can do it in PS3

Please advice on all.