DotNetOAuth re-login throws "This message has already been processed. This could indicate a replay attack in progress"

I am trying 开发者_JAVA技巧to use the DotNetOAuth library in my app to authenticate users. I am using code from the NerdDinner app and this scenario throws an exception

1. Lunch NerdDinner
2. Click on "Host Dinner" menu
3. Host Dinner requires authenticate so you get the login screen. I used Google to authenticate
4. After successful login, Host dinner page displays.
5. Now click LogOff
6. Click "Host Dinner" again. I selected Google again. This time I am presented "Allow Access" option. Clicking yes throws exception "This message has already been processed. This could indicate a replay attach in progress"

Any help in resolving the above highly appreciated

Thanks in Advance

I wonder if the URL you type into your web site initially (for example, foo.com) changes between the first and second times you log in (for example, to www. foo.com). That would explain Google adding an "Allow Access" check the second time. Also, if your site is automatically redirecting the user at an inopportune time (when the authentication response is coming back) you might be double-processing the auth response, which would cause the behavior you're seeing. So I'd double-check where you do your redirects.