Awesome. If you’ve been reading the IT News, you’d see Microsoft released a new RDP client for OS X and IOS on the 18th of October. I started experimenting with the IOS version on the day it came out and was very impressed with the client. I’ve since found time to install the OS X client, which theoretically replaces the version bundled with Office for Mac 2011. This new version is perfectly compatible with Windows Server 2012 R2 – without you needing to change the security settings on the server.
So if you have configured your Remote Desktop Session Host to use the RDP security layer instead of the TLS security layer, you can set that policy setting back to Not Configured, apply the GPO and restart the Remote Desktop Services service. I’ve updated my previous post (the one just before the new client was released), to point to this post. Happy RDPing!
~ Mike
Hopefully Helpful Hints // Mike J McGuire 
I have installed the new version and am still getting that same error. I went ahead and fired up my Parallels Win7 VM, and it connects just fine. RDC for Mac also connects to my old server, which is a WHS (Server 2003). Any idea why that might be?