I tested my RAM modules quickly. It passed one pass without error.
Today, I took my unneeded cards out of my computer to see if it could help and replaced my geForce FX by a geForce 2. I don't know if it helped, but after several attempts, I eventually could build the module (for the 96.xx driver as for the 173.xx one) with the Debian packages.
I still don't know where the problem comes from, but at least, I now know what to do.
Anyway, thanks for your quick replies.