[Plugin: WordTwit] Weird unspeakable failure on monthly archives

I’m not quite sure when this started – maybe 2.4.6 – but for some reason, some (not all) of my monthly archive links are now being redirected to single posts which aren’t necessarily part of that archive. Everything returns to normal when the plugin is deactivated, so I have to assume that it’s a problem with the plugin – but it doesn’t make any sense to me, and it probably doesn’t make any sense to BNC, either. I don’t want to lose this plugin, since it does the tweet work I need done better than anything else, but I can’t afford to lose access to those archives either. I’m using my own domain for URL shortening, though the same thing happens if I switch to bit.ly.