Hi Jeffrey,
Thanks for contributing to our forum. It definitely seems strange that you suddenly started receiving errors of this nature after posting several listings successfully yesterday. However, since these API errors eBay returned state that you do not have a valid payment method on file with your eBay account, I definitely recommend checking the status of your payment method first.
From your My eBay page, you can check the status of the automatic payment method you have on file with eBay by mousing over the “Account” tab, selecting the “Seller Account” option and looking in the section labeled “Payment methods for Seller Fees” on the ensuing page.
It seems possible that your credit card on file with eBay or Paypal may have expired as LifeIsLike suggested.
If your automatic payment method appears to be in good standing, I recommend contacting eBay's Customer Support team to see if they can provide you with any more information about why you are receiving these errors.
-Mike