I found a little piece in the nVidia README that mentions the kernel must be compiled with the same version of the compiler used to generate the nvidia.ko module. Funny thing is, the version of gcc on my system is 3.4.2 20041017 (Red Hat 3.4.2-6.fc3), that is also what the 2.6.10-1.741_FC3 shows to be the compiler used when I checked
rpm -qi kernel. So on a chance that it's not just the version difference, but the platform, I built me a custom kernel locally, then built the nvidia.ko module locally. So far, so good. In the past, I could kick off xscreensaver set for
Flow and the screen would freeze within five minutes.
I'll let things run overnight and see if it's still alive in the morning--fingers crossed.
UPDATE: It's 9am now and all is well.