Crash

there are no crashdumpps in there, so I will work off the info I have. At first glance Nvlddmkm.sys is your gfx driver, but just because the driver is shown as the issue does not mean it could not be an issue with the actual graphics card, just to make sure, run furmark as per this tutorial and we will go from there.

Video Card - Stress Test with Furmark

There are no crash dumps, because it is not a bluescreen.
A kernel power 41 means that the pc unexpected didn't have power anymore, this happens with a sudden shutdown or restart.
Unfortunately, I am not sure at what section the OP needs to be for this problem, but I would think it is the Performance and Maintenance section.

oh, ok then, still ru the test thoughas it explicitly mentioned your graphics

You might also consider updating Windows - :

Code:

Nome do AnfitriÆo:                            CELIO-PC
Nome do SO:                                   Microsoft Windows 7 Ultimate 
VersÆo do SO:                                 6.1.7600 N/D Compila‡Æo 7600
Fabricante de SO:                             Microsoft Corporation
Configura‡Æo do SO:                           Esta‡Æo de trabalho aut¢noma
Tipo de compila‡Æo do SO:                     Multiprocessor Free
Propriet*rio registado:                       C‚lio

Simply updating Windows to work better with later hardware drivers can often fix unexplained errors.