Brightness back to full after reboot

I see this problem on Linux Mint 16 Petra 64 bit as well, on an Alienware M14xR1 laptop.

Also, pressing the laptop brightness keys changes the screen brightness but does not update the "Brightness" slider in the "Screensaver and Lock Settings" panel of the "System Settings" app.

I'm experiencing this as well on Linux Mint 17.1 Rebecca with Cinnamon 2.6.7+rafaela. I haven't upgraded to Linux Mint 17.2 yet, I'll come back after I upgrade.

Asus U36S laptop machine
Kernel: 3.13.0-61-generic
Graphics (Optimus, NVIDIA chip turned off by default):

00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) (prog-if 00 [VGA controller])
        Subsystem: ASUSTeK Computer Inc. Device 2111
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
        Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
        Latency: 0
        Interrupt: pin A routed to IRQ 47
        Region 0: Memory at dc400000 (64-bit, non-prefetchable) [size=4M]
        Region 2: Memory at b0000000 (64-bit, prefetchable) [size=256M]
        Region 4: I/O ports at e000 [size=64]
        Expansion ROM at <unassigned> [disabled]
        Capabilities: <access denied>
        Kernel driver in use: i915

01:00.0 VGA compatible controller: NVIDIA Corporation GF119M [GeForce 610M] (rev ff) (prog-if ff)