Reinstalled the newest driver, emachines doesn't seem to have any new drivers on their download center
Why the heck are you looking for Nvidia drivers at emachine website? You should be using the drivers from Nvidia website or even here.
you could go try find some NVDA's external software that monitors GPU temperature. I work in this field and I've seen alot of overheated GPU's causing shutdown.
actually, try GPU-Z http://www.techpowerup.com/downloads/SysInfo/GPU-Z/ under sensor page, there should be info about temperature.
His video doesn't really have the sign of overheating or symptom but it's good to have a CPU and GPU monitor.
Sometimes the sensor is messed up so it would be good to at least make sure, since these tools probably use the same sensor to the ones that forces shutdowns. You know, just trying to eliminate one by one.
Depending on manufacturer, sometimes they have custom drivers. Take for example, Samsung Laptops. You might encounter problems with drivers using the NVIDIA standard drivers, best way to find out is to use the auto detect tool from NVIDIA's website. It will tell you there if you should use your manufacturer's drivers. Reason's why is stuff like hotkeys, etc.