Sorry – when it says "only letters or numbers" it is not kidding. This means no spaces, no underlines, in fact nothing that is not an, uh, letter or number.
We are at fault in that our Web Site currently allows you to enter these invalid characters – this will be fixed. In the meantime, try and correct your user names or passwords – if you cannot, contact support@eventide.com, giving your serial number, your old info, and your desired new info.