Depth problem - OpenSUSE Linux

[am577]

Just installed OpenSUSE 11.0 on a Dell Laptop. I have an OpenGL prog that works fine on my normal PC, but on the Dell there is an obvious problem with the 'depth'. Objects that should be hidden are not. It seems as if it might be using the 'drawing order' rather than the z coordinate to decide which objects are hidden behind other objects.
Is this a familiar problem ? Do I need a different graphics driver, for example ?
The graphics chipset is Intel 945.

[ZbuffeR]

I have seen some sloppy code that does not require a depth buffer at startup, as quite a lot of drivers always give you one.