This problem manifests itself when a client is connecting to a Windows host machine which is using the DX desktop capturer and and curtain mode disabled.  I do not see this issue if I use the GDI capturer or when I am using curtain mode.

The repro steps are:
1.) Set up a Windows 10 host machine (w/o curtain mode)
2.) Make sure the desktop is locked (so the user is asked for a password)
3.) Connect to the host machine (client platform seems not to matter)
4.) Click the logon overlay to dismiss it and reveal the password field

At this point the screen on the client will be frozen and I see several capture errors in our debug output.  If I enter my password on the logon screen and continue to the desktop, capturing begins to work again.  I can't find anything specific on MSDN, but I would not be surprised if the logon screen cannot be captured using DX, we need to address that problem or perhaps add a fallback path for the old capturer if there are other scenarios that trigger this problem.

Here is the example spew I see when this error occurs:
ERROR	c:\src\chromium\src\third_party\webrtc\modules\desktop_capture\win\dxgi_output_duplicator.cc	171	Failed to capture frame, error 006FBB30, code -2005270490
WARNING	c:\src\chromium\src\third_party\webrtc\modules\desktop_capture\win\dxgi_output_duplicator.cc	109	Failed to duplicate output from IDXGIOutput1, error 006EA1B0, with code -2147024891

The -2005270490 (0x887A002) error translates to DXGI_ERROR_ACCESS_LOST.