I was having trouble creating an RDP client for Mac to a Windows Server. When I RDP to tha same Windows machine from another Windows machine everything worked as advertised.
When I opened a RDP connection from my Mac to the Windows Server I would ge the following error: "Remote Desktop Connection cannot verify the identity of the computer that you want to connect to"
Since I was able to connect from a Windows Machine I was under the assumption that the RDP problem layed with my Mac. Wrong!
After trolling the internet for ages I finally found the fix.
How to fix the Mac OSX RDP Error:
On the Windows Server you are trying to RDP to perform the following
Ensure that RDP is enabled on the Windows Server and that the Firewall allows RDP.
Open the Management Console (mmc.exe)
Add the 'Local Computer Policy' snap-in
Goto: -> Computer Configuration -> Administrative Templates -> Windows Components -> Remote Desktop Services -> Remote Desktop Session Host -> Security
Change the following two settings from their default (be aware that there might be a reason that MSFT has decided to set them to default. It might be advisable to revise those settings after a new Mac RDP client has been released)
'Require use of specific for remote desktop (RDP) connections' from 'Default' to 'Enabled', then select 'RDP' in the options pane
'Require user authentication for remote connections by using Network Level Authentications' to 'Disabled'
Restart the 'Remote Desktop Service' or simply restart the computer
I was able to connect to various versions of Windows Server with this fix.
Credit -Microsoft Technet