open GL inconsistencies on different graphic cards

have been testing some of my jitter patches on a new macbook pro, and been having some issues with certain parameters not displaying properly. i have tested these patches extensively on older macs, so the only other thing i can think of is that the graphics card is interpreting commands differently...

the graphics card in question is NVIDIA GeForce 9400M on a new MBP 2.93 ghz.

the parameters in question are:

"line_width", the maximum line thickness appears to be much thinner than on previous graphics cards.

also under certain circumstances, textures also dont appear to map to objects in the same way as on older machines.

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i'm pretty sure this isnt coming from the patches as they have worked flawlessly on various older macs (laptop / desktop models).

can anyone think of anything else that could be causing these inconsistencies, or maybe there is a graphics card driver / or open GL update i need to install on the newer machine...

any suggestions would be much appreciated, thanks.

justin