Paypal Payments Standard disappears when Gold cart activated

Paypal standard is listed in the payment options when i have gold cart plugin deactivated but on activation standard disappears and only the other ones remain.

I’d like to know what could be causing the problem please, the website is http://prepperstock.com/

I’m using wp e-commerce version 3.8.12.1 and gold Version 2.9.7.5

thanks in advance

jess

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