I tried my own experiment, outlined before. Went to the hard disk manager, deleted every save game I had, as well as the KOTOR heading. Started a new game (my third, actually, since the bug first appeared). This time, work benches are working again. I admit to a bit of perenial worry about whether they're suddenly going to stop again, each time I try one, but so far so good; just about back out of Peragus.