Okay, update: now, several days later, it's again changing the color of the already-opened topics in Archives!
Just as inexplicably as when it ceased, it's resumed. Hope it lasts. (Actually I haven't checked it yet today -- "stay tuned"...)
Thanks, everyone, for your input. It helps to know it's not something we've personally been doing wrong all of a sudden.
Last edited by postal packin' mama; 12-16-2011 at 10:16 AM.