I've run various kinds of kernels on this machine and all freeze randomly, I think it may be a hardware/BIOS/Firmware related problem. But I'm not that sure of it and that's why I'm filing a bug report. I need some help to figure out what kind of a failure this is. The motherboard of this notebook has been replaced due to a BIOS update failure but the random freezing still exists. I think it's something related to nVidia Optimus and or Intel i915. The following link is to an photo that I took while it was hanged. http://img26.imageshack.us/f/dsc00037ia.jpg/