Weird behavior

Hello everyone,

With the 6.1.2 version, it shows weird behavior.
Here http://i.imgur.com/FhySTEm.png I'm taking the 'n' but it says
illegal move (but stil moves it)
Afterwards, I'm playing the black !!!. So I move, it says illegal move
(but still moves it), and I'm playing the white again, and after it
freezes (thinks for very long).
Second screenshot with Unknown command error : http://i.imgur.com/eXGtsRi.png

Any idea what is causing this behavior ?

Thank you.
Regards,

-- 
~ktr