Problem with fragment.color.secondary, specific to Forceware 91.47

I’ve recently changed my Forceware version to upgrade to 91.47 (same with 91.31).

My programs are using the fragment.color.secondary channel between vertex and pixel programs.

So far everything was OK, but with the new forceware version, I can’t get anything but a black color from this channel.

I’ve reproduced this with these cards: 6800GT, 7800GT, 7950GX2.

This sounds like a driver bug, but maybe I’ve missed something else ? Don’t know what to do to solve it.

Thanks for any assistance