I've found a problem with RDP where a user connecting remotely will receive the error:
"The credentials that were used to connect to 192.168.0.20 did not work. Please enter new credentials."
"The logon attempt failed"
In Event Viewer you will see the following errors:
Event ID: 226
RDPClient_SSL: An error was encountered when transitioning from TsSslStateHandshakeInProgress to TsSslStateDisconnecting in response to 8 (error code 0x80004005).
To resolve this:
On Windows 7 you will need to RSAT (Remote Server Administration Tools) from this link. Windows 8 / 8.1 this is installed already.
Run GPEdit.msc from either the Run box or the Start Menu Search.
Browse to the following path
Local Computer Policy\Computer Configuration\Administrative Templates\Windows Components\Remote Desktop Services\Remote Desktop Session Host\Security
Set the settings for the following two settings:
"Always prompt for password upon connection" to "Disabled"
"Require user authentication for remote connections by using Network level authentication" to "Disabled"
Reboot the computer and you will now be able to connect via RDP when no user is logged on locally.