I've never had problems with the nvidia driver
either, until I used the
realtime kernel (2.6.20-rt8) and the MX4000. The latest nvidia driver
doesn't support this chipset. There is a patch for the rt kernel and the
nvidia v9631 drivers (the last version to support the MX4000) but I
couldn't get it to work (I didn't have time to try very hard, though.)
To compile the driver, one needs to either restore the "transitional"
#define SA_.... stuff to interrupts.h (the rt8 patch had no business
removing them!) or apply a patch to the extracted nvidia sources and then
compile that.
What rt8 kernel patch are you referring to and where does one get it?