I am using the latest version. I succeed in installing the newsletter now (i don't know how) but to answer your question I rebuilt the database many time.
However now I have another issue, I try to build a Widget to perform a quick subscribtion, with only the email as a requirement but i each time I try to complete the form in the widget I got a blank page and this is the url that i get:

http://www.mysite.com/WidgetFormProxy/index/44?executeForm=QuickSubscribe

I have been trying on this for two weeks now without much luck. Maybe you know something about this?

I have tried that but it did not solve the problem with my widget whereas it was working on previous version!