Switching off screen = switching off bluray

[ash_scotland88]

Twice today, been watching a bluray on one half of the screen, went out omy room and force of habit switched off the screen. Both times it's "switched off" the bluray, windvd reverts back to it's welcome screen. It also doesn't give me the resume option.
Any idea why?

 

[Fanatic]

Because of the High-Bandwidth Definition Content Protection (HDCP).

If you had pirated the film you wouldn't have this problem

 

[ash_scotland88]

is there any point in me asking how/why do they do that?
I had to revert back from using displayport due to when ever I switched off the screen it changed the sizes of windows I had open.