Load denied by X-Frame

Hello, every time a user tries to proceed with checkout, the paypal page fails loading.
This is the error i get:

Load denied by X-Frame-Options: https://www.paypal.com/it/cgi-bin/webscr?cmd=_flow&SESSION=juyZcvAaWiBVj-Cq5MGuxOGozrzhzQo45w-VcBeeA6yom20wBVrFkpViOfy&dispatch=50a222a57771920b6a3d7b606239e4d529b525e0b7e69bf0224adecfb0124e9b61f737ba21b081986471f9b93cfa01e00b63629be0164db1 does not permit cross-origin framing.

What should i do?
Thanks for help.

http://wordpress.org/plugins/wp-e-commerce/