PLEASE HELP URGENT - 520002 - Internal Error (Paypal Chained Payments)

Please I need URGENT help.

I have 4 new shops opening today, and ive just done a test sale and Im getting this error on all shops. Including older ones.

All I have done is installed Pro-sites (which looked like it had been working mint) and now now PayPal sales are working.

"There was a problem connecting to PayPal to setup your purchase. Please try again.

520002 - Internal Error"

Please I need help ASAP as I have shops expecting to open today!

I just googled and found this although its a few days old, could it be related? Can anyone confirm if their shops are working (chained payments).