I had problems to connect with RDP (Windows Remote Desktop) from a Windows 7 client to a Windows 2008 Server. Although I used the correct user and password and this user had the rights to connect via RDP, I always got the error that my credentials are invalid.
The server had been configured to show a logon warning message before displaying the logon screen. In this case you need to add the following parameter to your RDP file on the client for your RDP session:
After that you should be able to login to the server without problems.