Update in Paypal's Backend
In CVS, paypal's payment module has been updated with some changes made recently in paypal's backend.
21st April 2001 by Harald Ponce de Leon
For those of you using 2.1 heres how to fix it:
Edit the file catalog/includes/modules/payment/paypal.php.
Look for the line with https://secure.paypal.com
Change the bit: