Errors wtih Not-Logged In Customer

Over the weekend I received a set of error messages (emailed to me) giving me an error with Pay Pal. I'm not quite sure what the messages are trying to say and I am NOT seeing a completed order either in the back-end or with money entering my Pay pal account.

I am trying to duplicate (and fix!) the problem

When I purchase something from my cart with my personal pay pal and am NOT logged in, (Express checkout) I get emailed error reports.

But, the money does go all the way through to my business pay pal account.

I am thinking it has something to do with a customer address but I'm not really sure. ALL my products are digital so I don't need an address.

I don't get the error when I AM logged in. (I don't think...) Is there any way that someone can take a look at the error logs and give me a clue as to what is wrong? Error reporting IS on but I'm not sure where to find the logs besides in my emails.

Thanks!