I just get a black screen remoting (RDP) into Windows 8 box

This Technet thread suggests:

1. Type Ctrl + Alt + End
2. Then cancel
3. Then exiting and reconnecting

You could also try disabling bitmap caching using this KB article.

Open the Local Group Policy Editor on the machine you are running the Remote Desktop client.

Under Computer Configuration>Administrative Templates>Windows Components>Remote Desktop Services?Remote Desktop Connection Client

Enable the setting called Turn Off UDP On Client

Now I'm able to connect without issue... somehow UDP isn't making it through and this change fixes the problem!

Should anyone wish to change the setting from registry rather than through group policy, here's the place to do that:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Services\Client

Create\set fClientDisableUDP (REG_DWORD) to 1.

PS> Set-ItemProperty -Path 'HKLM:\SOFTWARE\Policies\Microsoft\Windows NT\Terminal Services\Client' -Name fClientDisableUDP -Value 1