if i go to power management settings and set "turn off the display" to "never", then push save, i get no error, but, if i go AFK for 20 minutes, then the display still turns off.. and when the display turns off, if i go into power management then the setting is at 20 minutes again, as if the option didn't save properly, because if i save it and immediately open power management again, then it shows the setting as "never".

how can i fix this problem? any suggestions?