I've been tasked with looking at a Magento CE 1.6 site that has PayPal standard Payments as the payment method. When a customer goes to pay for an order the PayPal redirect works but the customer gets an error page on PayPal with error code 3005 and a message saying that PayPal is experiencing temporary difficulties which means the order gets left in 'Pending Payment' in Magento. I've pointed a local install of the site at the PayPal sandbox and orders go through fine. I also do not have access to the live PayPal account.
Now, I'm presuming that PayPal isn't actually having any issues as such so if anyone can help as to what may be happening and how to fix it that would be great.