Comment 14 for bug 844241

I am running Ubuntu 11.10 32 bit on a Lenovo B570 and can confirm this bug.
See the attached screenshot for the settings.

After one minute the display is turned off and neither moving the mouse or pressing keys will reactivate it.
No messages appear in the syslog.

Pressing FN+UP (increase brightness) however does turn on the monitor, setting it to minimum brightness (that is: the first step with actual brightness, not off). If I keep holding down those keys the screen will brighten up to the normal, fully usable level.
When pressing FN+UP the syslog gets flooded with the following messages:

Dec 18 12:41:52 laptop32 kernel: [ 930.178719] ACPI: Failed to switch the brightness
Dec 18 12:41:52 laptop32 kernel: [ 930.251163] ACPI: Failed to switch the brightness
Dec 18 12:41:52 laptop32 kernel: [ 930.323450] ACPI: Failed to switch the brightness
Dec 18 12:41:52 laptop32 kernel: [ 930.676270] ACPI: Failed to switch the brightness
Dec 18 12:41:52 laptop32 kernel: [ 930.889567] ACPI: Failed to switch the brightness
Dec 18 12:41:54 laptop32 kernel: [ 932.370370] ACPI: Failed to switch the brightness
Dec 18 12:41:54 laptop32 kernel: [ 932.565523] ACPI: Failed to switch the brightness
Dec 18 12:41:54 laptop32 kernel: [ 932.750587] ACPI: Failed to switch the brightness
Dec 18 12:41:58 laptop32 kernel: [ 936.317939] ACPI: Failed to switch the brightness