I am having the same problem and there doesn't seem to be any answers on the help site. I called them on 08703522000 (I'm UK based) and they are looking into it. They wanted me to sent them a print screen of the error message.
I've had this problem for over 2 years and I haven't been able to find a solution. The address I want to add, disappeared from my list sometime back and I've been trying to re-add it without success ever since.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.