Thanks.
Yesterday I erased the hard drive again, but I used Migration Assistant only for my networking preferences. I'm slowly reinstalling everything else one piece at a time.
I didn't use the 10.6.8 combo updater. I installed the 10.6.4 update, then 10.6.5, etc., and stopped at 10.6.7. I haven't yet checked to see if the font problem will return in 10.6.8.
Here was my thinking. When I bought this iMac in 2006, it came with 10.4.7. installed. Considering all the installing I did over the years, including systems, including multiple system installs and reinstalls, there was plenty of opportunity to accrue crud. I did so much tinkering. You get the point. Lots of files were on the computer whose purpose eluded me, and the opposite, who knows what got deleted over the years deep into the system. There's a lot to be said for starting from scratch, with original factory equipment.
For example, these files in Sys>Library>Fonts were not original equipment: encodings.dir, fonts.dir, fonts.list, fonts.scale. I don't know what they do. I recall deleting them in the past and keeping them, trying both, but I still don't know. Possibly they are from a third party program.
Second example: Software Update told me to download ProKit Update, which I had never seen before. It claimed "improved support for Font smoothing", among other things, so of course it got my attention. "This update is intended for users of Final Cut Pro, Motion, Soundtrack Pro, DVD Studio Pro, iPhoto, Aperture, Final Cut Express, Logic Pro, MainStage, Logic Express and iAd Producer." That's not me, but I installed the update anyway to see what would happen. I didn't notice any change.
