I can confirm this on Toshiba Sattelite Pro U200. Until Xorg is started, changing brightness works as expected. When Xorg starts, it's like every time i change brightness, system does dpms off. If I keep pressing Fn+F6/7, eventually screen will appear again.
In my case, Xorg doesn't crash, it just puts screen 'in sleep'. And yes, blacklisting video ACPI driver resolves this issue. -- X crashes on brightness change on couple of laptop models https://launchpad.net/bugs/70073 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
