I have an NVidia GeForce 8600M GT. It's the highest my computer will take.
Looks like you're using a Laptop. Going by the Graphics Card.

The thing is that sometimes it works, and other addons like the C-130, B-52, or 767 work just fine
Those aircraft do not use HD textures (yet) so that is why your computer can handle them easier. Even I can get the occasional graphics issue with the 707 and my GC is a GTX470. I really think that is the main reason for your problem.

Mark