Brightness setting by pressing HotKey or adjusting the display brightness value in "Windows Mobility Center" cannot be saved after sleep or hibernate - Notebooks
The display brightness can be changed by pressing the HotKey command (Fn+Home or Fn+End) or by adjusting the display brightness in "Windows Mobility Center." After resuming from hibernation or sleep mode, you may notice that the display brightness is not the same as it was before entering hibernation or sleep mode. The display brightness in the selected power plan is set.
Any ThinkPad or 3000 Family notebook running Microsoft Windows Vista.
After resume from sleep or hibernate, set the temporary brightness level again by the HotKey or in Windows Mobility Center.