I have tried the same problem, not only with Lineage2, but everytime i tried loading a 3D game my computer would per default shut down / power off (without notifications) and restart..
The problem is that everytime you load a 3D game the graphic card will consume more ampere/power from your power supply - because it is clocking up to 3D settings .. and since it seems you have a too small power supply it will just shut down instead of loading the game.
Solution to my problem was to get a larger/better PSU (Power Supply).