Dell Vostro 3700 shutdown during graphics stress test

Hi,

I have a Vostro 3700, i7,  8GB RAM, with Nvidia GeForce GT 330M.

When I run the "PC Check up" hardware test for the graphics card, the laptop shutdown a few seconds after the test is initiated.

This also happens randomly when running a rendering application called "Poser".

I have the latest driver for the graphics card installed, downloaded from Dell Support page.

I have cleaned the fan and replaced the thermal paste to avoid overheating. The laptop is not too hot when this happens.

Any idea of what is causing this? Is this definitely a hardware problem or could it be something else?

Thanks in advance

Luis