Solved: I am using a computer I built myself and I have overclocked the processor to 2.60GHz when it supports 2.00GHz and I got 4270 3DMarks and when I undone the changes, it kept shutting itself off. I cleared the BIOS and I still keep getting problems.
Startup Repair can't even fix it and I sometimes got the BSOD. It also shuts down by itself as if I was in a power cut and I keep losing unsaved data I spent several minutes or even hours on.
I even keep getting unexpected shutdowns even when I am using the BIOS.