It has just happened to me once. I hope it won't happen again... If you are having problem frequently you should use moneybookers or something like that.
I just had 1 similar issue with PayPal, but it was for just couple of hours and it was different from what you see (the message I saw was in the PayPal page design itself, just there were no login form etc...).
I have seen it a few times. I hate paypal and stopped using them a few months ago. Although some people do not like Epassporte, I tend to use them and EPassporte.
A huge amount of people is using paypal and I think this is quite normal to happen from time to time.