Selective Black Screen on remote computer with RDP

My computer (Win7 - "A") used to log into another Win7 - "B" perfectly.
Yesterday during an RDP session on logout it lost the background and only offers a black screen.
Now If I log into Win - "B" I get a black screen.
However if I RDP into Win - "B" from a Mac it works normally.
It gets worse:
If I RDP into Win - "B" from another Windows machine I get the same black screen.
But if I log in to another windows machine from Win - "A" that works fine.

Where should I start looking?

I have tried changing the resolution, tried sending Ctrl+Alt+End, creating a new Account - nix!

Any advice please?

Jean

Quite a conundrum! Are all the Windows machines kept similarly updated, the remote desktop updates in particular? Were there any updates or software changes to B recently?

My only other suggestion is to open Group Policy Editor (type gpedit.msc in the start menu text box) and see if any of the Remote Desktop settings are different between the machines:

Computer Configuration > Administrative Templates > Windows Components > Remote Desktop Services

Well I am in fact doing a windows update on Win "B"
One of the threads I read spoke about uninstalling KB 2830477 but in fact that had never been installed on the machine in the first place.
I'll have a look at gpedit.msc - thanks for the idea.

Hello again, I couldn't see anything obvious so I decided on a system restore on the target computer - Win "B" to a point in the past before the problem arose. Guess what? Still black! At least that identifies machine "A" with the problem. The puzzle is that any other machine RDPs normally with Win - "A" So I guess the question is - where does RDP store information on the connection? I will delete all saved files and retry.

I give up: The restore did nothing for me; deleting the saved RDP file did nothing - frankly who has the time to sort out Microsoft-induced conundrums? That sounds defeatist I know but...