Remote Desktop Connection client 6.0 introduces new authentication features to improve security for Windows Vista and Windows Longhorn Server, which makes it mandatory for the user to enter logon credentials before RDP client can establish connection to the remote server (" Enter your credentials for <server>. These credentials will be used when you connect to the remote computer" ). But if the remote machine is configured to show logon warning message or if the remote system happens to be Windows 2000 or XP, you’ll need to enter the credentials again at remote machine’s logon screen.
There is however a workaround to skip the credentials screen that RDP 6.0 client shows by choosing “Do not attempt authentication” under Authentication options on the Advanced tab, but this option is not set permanently. To permanently skip the additional credential screen of RDP 6.0 client, edit the Default.RDP file in notepad to include enablecredsspsupport:i:0 . The Default.RDP is located in each user’s My Documents folder. Including enablecredsspsupport:i:0 disables the Credentials Security Service Provider for the connection. If you use separate .RDP files for different server, modify each of those .RDP files. Below is the content section of the default.rdp file with enablecredsspsupport:i:0 option included.
prompt for credentials:i:0
negotiate security layer:i:1
Note that this workaround is suggested only if you connect Windows 2000/2003/XP systems because according to Terminal Services Team blog post – “This option does disable the new credential prompting behavior, but it also disables support for Network Level Authentication for Vista (and Longhorn Server) RDP connections; Network Level Authentication requires credentials to be provided by the client before a session is created on the server side.” So if you do connect to Vista/Longhorn over RDP, you’ll not be able to use this option.