This issue could also be caused by the anti virus software that is installed on the workstation. Some anti-virus software such as web root or malwarebytes have been known to cause these issues with credit cards in Altru. Try turning off the anti key-logger associated with your anti virus software. Then try to process your credit card and see if the error messages stop. If you are using the Webroot anti-virus software, you will want to disable Identity Sheild.
Note: For steps on disabling the anti key-logger, please reach out directly to your IT Department or Antivirus Vendor. Since this is a third party software, it is beyond Blackbaud's scope of support.
Alternatively, you can switch to using Chrome to print tickets and receipts.