I too am having this problem on a Dell D430. In addition, the stepping on the brightness keys is wrong. It seems to step from the bottom, then from the top etc. etc. So when increasing the brightness, it goes dim, halfbright, dim+1, halfbright+1, dim+2, halfbright+2..........etc.
I too am having this problem on a Dell D430. In addition, the stepping on the brightness keys is wrong. It seems to step from the bottom, then from the top etc. etc. So when increasing the brightness, it goes dim, halfbright, dim+1, halfbright+1, dim+2, halfbright+ 2...... ....etc.