Thanks Figaro :) So I looked in the wp_options table and there was no active_plugins table, although there were some records for plug-ins one level up with all the rest of the tables. Here's a thought: it occurred to me that I made the "log-in" page not public in the dashboard -- maybe that has something to do with it? At this point I'm about to just try to roll back to the previous version as best I can.
As a side note: I totally understand the concept of Wordpress with it being free and open source and whatnot -- and I think it's a great idea and very much appreciate all the time and effort that so many folks put into it. But honestly, I feel like I spend as much time tracking down answers to these maddening problems as I do with creative content and I'm beginning to wonder if my time (and time = money after all) wouldn't be better spent getting some user friendly commercial software to build my sites. Any suggestions? I mean, is WP and the seemingly endless tinkering and forum lurking required the best and most convenient thing our there?
Sorry for the rant :) It's just that getting everything to work like it's supposed to has become a bit of an unraveling sweater.
Thanks again to all who have responded.