To work around this problem, turn off the new features in Remote Desktop Connection 6.0 to revert to the features in Remote Desktop Connection 5.x. To do this, follow these steps:
Click Start, click Run, type mstsc.exe, and then click OK.
Click Options, and then click the General tab.
Click Save As, and then type a file name in the File name box.
Select the location where you want to save the remote desktop file, click Save, and then click Cancel.
Note The saved file has the .rdp file name extension.
Click Start, click Run, type notepad, and then click OK.
On the File menu, click Open.
In the Files of type list, click All Files.
In the Look in list, locate and then click the file that you saved in step 4. Then, click Open.
Locate the line that resembles the following:
Note The n placeholder represents the current authentication level.
Change the authentication level to 0 so that the line becomes the following:
Note When you set the authentication level to 0, RDP 6.0 does not check for server authentication.
Add the following line to the end of the file:
Note When this line is present, you do not have to provide credentials before you establish a remote desktop connection.
On the File menu, click Save.
To connect by using Remote Desktop Connection, run the file that you saved in step 12.
Note After you follow these steps, the new security features that Remote Desktop Connection 6.0 provides are removed. Additionally, Remote Desktop Connection 6.0 becomes incompatible with Windows Vista-based computers that have the Allow connections only from computers running Remote Desktop with Network Level Authentication option enabled in the system properties.