Game make PC Crash

[Alcades]

I have played for a couple of weeks, but actually when i am playing, after somekind of 10-20 minutes, the game totally crashes my computer.

The screen become frozen and even the keyboard stop working (the Num Lock button get off) and no comands respond, like Ctrl+Alt+Del doesnt work, just like the mouse.

The only way i can solve this is by turning off computer and starting it again. But this keep happening every 10-20 minutes of gameplay.

Someone got the same problem? I would like a way to play without crashing my computer every time :/

Thanks for the help.
My computer got a 512 mb ram and pentium 4, with geforce 5200 video, this game isnt that heavy to crash it O.o