I made a contribution and Paypal came back with this message.
It's probably not a problem, I've never seen this kind of message.
Your payment is being reviewed because of regulations.
We're working fast to resolve this. In the meantime, here's some information about the situation:
We usually complete this process within 72 hours, with your cooperation.
For now, this review only involves this transaction and does not affect the use of your PayPal account.
We'll send an email soon to keep you in the loop, and will follow-up with you when it's complete or if we need more information.