Searched the forum and there have been similar issues with other people, I set up the paypal plugin exactly as described in the documentation. I notice from another post in the forum that you have to edit a file and then FTP it back to the server, but the particular file that is mentioned is blank in my install. I'm very confused, when you go to pay via paypal it says there has been a fault. Exactly like in a similar post, I completed the relevant IPN details etc, still no joy help please.
It may help if you paste exact error message and exact URL where it happens (you may skip your domainname).