My PC restarting by itself sometimes, when the stages giving mission requirement or at the end of the stages and giving results. I wonder what's wrong with it? D:

game prolly conflicts with your system... kinda edgy to recommend this but.... reformat? Just consider this as your last option.

Try and turn off the animations. If it helps - reinstall the video codecs.

I tried turning off all the animation but my PC still restarting by itself sometimes. Thanks for the advices though, I wonder what went wrong. x_x

Does it restart while playing kamidori only? Or do you have the same problem with other games/software?

Only Kamidori, other games and applications works fine for me. xD

One thing I've noticed about kamidori is that the video (or audio codec, not sure ) icon appears constantly in the system tray (in WinXP) especially during critical hits in the battles. The game blends in video animation in-game. So it may be what as xenos said - proper codecs. Which proper codecs, i really can't say.