Personally I would tick the button and let the system mange the pagefile size.
And you are corret Kernal 41 is becuase its not a controlled shutdown as forced off while holding power button.
Overheat due to faulty / blocked fans - speed fan will show temperatures
PSU voltages - speed fan will also show voltages
Household power surges fridge etc switching on/off
faulty memory stick try memtest click here virus or spyware scan for both especially if shutting down with in a few minutes of switch on or internet use
driver conflicts especially graphics cards get the latest drivers for your equipment