Firstly (and most importantly) : update everything you can... Install all windows updates and then go to VAIO update and install all updates available, there are always some minor updates available in the control center that might fix your problem even it might not seem to be!
Secondly : depending on your country/region of purchase of your laptop, check the online support website for messages and software updates. These updates might be available ONLY in the official website and not through Vaio update software.
Trying to fix system settings are not likely to help at all, I tried many many ways and finally for me, the NVIDIA driver seemed to be the source of the problem (it was outdated). It might be another problem for you, and there is no need to change your power settings - they work best when allowed to operate in default mode.