There's a lot of chatter a/b Helvetica in most of the threads I've been reading. I don't have Suitcase as a log-in item (Fusion 4 doesn't need to be running in the background the way older versions did). But I did see several mentions of clicking the "Stop Type Core" button in Suitcase preferences.

Since I have very limited need of any of the Helveticas in my work fonts folder, I'm going to start by deleting those sets and see what happens after another safe boot sequence. Only if that doesn't help will I try messing around with the steps outlined in those two guides. But having once experienced how font problems can bring a system down, I'll take those steps only as a last resort.

Wish me luck...