Tim seems to have passed his OS X infection to me…

No sooner does Tim Bray report that his OS X bitrot has been cured by 10.3.4 than I suddenly find it affecting me. Specifically, iChat refuses to launch; it bounces in a desultory fashion a couple of times and then exits. I’ve deleted all of the obvious prefs files, repaired permissions, run the iChatAV update… nothing. And none of the log files [why does OS X have so many of them?] shows anything untoward….
People may tell me that this is an excellent excuse to start using Adium X, but I’d prefer to make the move voluntarily rather than in desperation.
[Update: Adium is working fine for me, but I wish I knew why iChat is broken.)