I use Eurosoft PC Check to figure out my problems, it test each piece of hardware in your computer with the exception of the power supply of course.
Its a pricey piece of software $299.99(made a copy from my office), but it works.
Halflife 2 to me has to take the cake, i really felt like i was apart of the story. If you take your time to look throughout the level and every area you can; you find so much background story about what is happening that isnt said directly through npcs. Also i enjoyed the more realistic feel of...
1. Overheating
2. faulty psu
3. a loose plug wouldn't short it out but it would shut it off if it loses that connection.
4. Its possible that one of your components are shutting it off.
5. Virus?
6. System file corruption.
If its a movie that is made completely in 3d(mostly animated movies) then its worth it, but if its one of those shitty movies where they add the 3d effects on top of a movie(almost every movie that is coming out right now which is pathetic)....then you just wasted yourself thousands on a piece...