On my EEE PC netbook some colors are not displayed properly. Specifically, dark gradients such as in the window title do not look very smooth, but rather look like a sequence of a couple of different colors.

This is especially visible when opening a menu, for example the "File" menu in Firefox. As you know this one is black, and it looks terrible on my screen. It is not just black, but the colors look really graded and far from a smooth gradient or anything.

Now I am wondering: Is this a hardware or software issue? And how can I check this?
If it should be a fixable problem I think it would be worth another question.

Note that I am using Natty. If my problem description is not good enough I can try to take a photo.