While repairing permissions i figured the problem is the external display (it shows displaypolicyd being fixed)...so, i booted without the external screen (connected with hdmi-vga convertor), and it worked (kext-dev-mode=1)...however, if i try to connect the monitor, it will get a kp and reboot.
So, the only way i can use the external sceen is booting without kext-dev-mode=1. I have to say though, that while using the probook after booting that way i didn´t notice anything not working besides sound...
Anyway, i´d like to find a way to fix this screen issue...