MMOViper.com

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

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).

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.