If the login window keeps on showing up even though you are certain that you have entered the credentials that you have received via email, you are most likely facing an issue with Internet Explorer where it automatically appends the local domain when sending the credentials. Unless you are using Internet Explorer 7, to work around this issue, please specify the username in the following form: ".\1234", without the quotes. If you are in fact using Internet Explorer 7, the recommended username format is "user1234", without the quotes.
If the login window fails to appear, your network settings may be preventing access to our server. Some users have mentioned that their corporate firewall was blocking access to port 8080