I am running a Mac mini as my iTunes media server. I control it by screen sharing in with my nMBP and showing the output on the nMBP and on a 50" Sony via HDMI. It used to run ok, but now (Yosemite 10.10.1) every time I try to play an iTunes movie I get a 'The movie can only be displayed on displays that support HDCP'. The display must support this as it used to work ok? Anyone have any idea what the problem could be?