It turns out that my problem was a special character, an exclamation mark (!) in my password. The forum site accepted it, the download site did not. Once I changed my password, the problem went away.
I've registered here and while logged in, when I attempt to download, I get a page saying "Please Login Permission Denied" When I enter my username and password, I get the message "Please Login Invalid Password" However this is the same password I am able to use to successfully log in to the forum. Am I missing something here? Thanks for whatever assistance or information you can provide.