That's indeed the usual reason for such a problem. The Geforce 9 is detected, but does not work properly with DirectX 9.

This can happen when you plug in a new 3D card, but don't install its video driver, or install a wrong driver. The owner of that PC should first deinstall all previous video drivers completely, then install the recent DirectX version, and then the proper GF9 driver, ideally the recent driver from the nVidia website.

Of course, it can be something completely different, such as a too weak power supply for the GF9. Then it can sometimes work and sometimes not. But in 99% of all those cases, it's a wrong video driver. Despite all claims to the contrary, other DX9 games won't then run either.