Render fuzziness now on Mac 10.4.4

For some reason, I can no longer get a clean image when I render with Blender via Yafray 0.0.8. This applies to all the versions of Blender I have for the Mac - 2.36, 2.37a, and 2.40. You can see a sharp image that I rendered about five months ago with a 10.4.1 version of Tiger at this location:

http://www.pixies.iinet.net/images/peacekeeper_icon_small_1.jpg

and you can see a recent, now dappled, render, from the same mesh, but with Tiger 10.4.4, at the following location:

http://www.pixies.iinet.net/images/Blender_2.40_sample.jpg

I get the same dappled effect regardless of the version of Blender I use, so it isn’t a Blender problem, but perhaps something in 10.4.4 is the issue. I did upgrade my RAM to 1.25GB recently, and that might be an issue as well, but before I go replacing memory or down-grading to an early version of Tiger, I’d like to ask if anyone else has experienced this reduction in render quality since moving to 10.4.4.

I’m using a G4 iMac with Tiger 10.4.4, 1.25 GB RAM, GeForce FX 5200 graphics card.