power management: screen doesn't blank

[vangop]

Hi!
I've noticed that power management stopped working for my screen.
I have an option to sleep display after 5 mins, but it stopped working. I also set a screensaver to blank screen in 1 minute - no result as well.
This used to work fine, just stopped.
I installed gnome-do and cairo-dock, guess that's all since.
It doesn't blank the screen even with closed lid, although set to do so.
Thanks!

[vangop]

Everything works fine after restart. Then something breaks again. I need to find what inhibits power management.
Anybody? How can I troubleshoot power management?

Finally found out. This is vlc that inhibits PM. On win you can pause it and it will restore PM, on linux you have to stop the video.