credit card issues

I have searched with zero luck. We continue to have the problem where people are entering their credit card and when they process, it
just erases the credit card number. It is an endless loop, There is no error code given. I do not think it is a paypal thing because it happens instantly, no processing time is taken(the typical 3-5 seconds one sees where paying online. As soon as they process. 8 people today. When we login as them and try on the front end, it fails as well. Once the credit card info is filled in and you hit pay, the card number erases and the card validation code appears(bluebox). If we run the transaction back of house, no problem. All of their info has been correct in the orders.
All credit car, address, number info is correct. This accounts for 5-10 calls per day.