It's within hailing distance. The difference from what I did, versus what you suggest, is that I haven't installed 10.6.8 yet. I did migrate my network prefs, and nothing else, w/Migration Asst. I've been using my installers to reinstall my third-party software. I could have held off on that. It is possible that some some third-party program is causing the problem.
I think it's more likely that I screwed up by deleting something I shouldn't have during years of tinkering. Another possibility that's occurred to me is that there is something about the factory installed software (and hardware, I guess) that it is particular to this model Mac. Messing with that would therefore lead to problems. I can't help thinking that, particularly under the latest regime, Apple has no intention of letting people hold on to their computers for ten years like I have, and thefore has no intention of allowing people to upgrade system after system on their hard drives.
I could clone my drive right now, then install 10.6.8 to see if the problem returns. But I have only one backup drive and I'm using it now. I'm considering buy a second hard drive anyway.
I got an email from Kurt Lang, whose great site about fonts I spent a lot of time with. He wrote, "Whatever’s going on, it’s not the fonts. Fonts are vector shapes and cannot themselves be jaggy. Something is causing them to be drawn badly by the system. But I don’t know what that would be."
Is the ATI Radeon involved in drawing fonts?
I was able to reproduce another problem I had of kernel panics when webgl and hardware acceleration were enabled in Firefox. Certain web sites would take down my Mac. That started happening about three years ago.
An updated ATI driver would be interesting to try, but obviously that's not going happen.
The lesson there is that I need to pay close attention to the graphics card the next time I buy a computer, which very likely won't be a Mac, so it probably won't be a problem anyway.
During the past year, I've been debating what do to next in my computer setup, and I've almost concluded that I'm done with Apple after thirty years as their customer. But that's a different thread. I can discuss that in the Lounge, or wherever appropriate, if anyone wants.
Thanks to everyone who has responded.
