I believe this is because I had to change the cookie setup and for some reason your browser hasn't gotten the new cookie.
This should solve it:
First, go to the forum homepage and hit the link at the very bottom that says "Delete cookies set by this board". This should log you out.
Then (from Microsoft):
QUOTE
To delete Internet Cookies in Internet Explorer 5.x.
Start Internet Explorer
Click Edit, and then click Preferences.
In Internet Explorer Preferences, double-click Receiving Files.
Under Receiving Files, click Cookies.
Under Cookie Settings, select the cookie(s) you want to delete.
Note: To select all cookies, press Command+A.
Click Delete.
Click OK to close the Internet Explorer Preferences window.
Lastly, I would close all Internet Explorer windows you have open.
Then, open up Internet Explorer, go to the site, log in, and you should be set.
If it doesn't work, let me know and I'll do some more research.
Mike
**** ADDED: Up there where it says "select all the cookies you want to delete", you can either delete all of them (recommended), or find the America's Debate cookie(s). It would be called something like: .americasdebate.com or forums_americasdebate.com or www.americasdebate.com or just /forums/. That's why I recommend clearing all of them.