And yes, I entered in lowercase. All I get is :
This server could not verify that you are authorized to access the document requested. Either you supplied the wrong credentials (e.g., bad password), or your browser doesn't understand how to supply the credentials required.

Are you still having this issue?

Yes ; tried with Vista and XP, and I can't download. It seems like if I put wrong username/passw (3 try and failed message).

If you can access the forums, you should be able to download. The only thing different is lowercase for usernames.

Resolved : I closed this account and opened another one. It works fine with the new one.