Hey, I'm not sure what to tell you. My Optimus functionality has been working since installing the "newest" version of the official Nvidia drivers (nvidia-352) on LM17.3. I turned it on in the BIOS and have been able to select from the "NVIDIA X Server Settings" utility ever since. I remember trying out Bumblebee on LM17 and having similar issues as you mention, and was unable to boot with Optimus enabled in the BIOS.