Well, somewhat unsurprisingly, LR suggested I take the plugins out and see if the crash recurs.

Which is probably what I would've said. Which is great, but I have no way of reproducing...
Problem is, I don't really know what PluginAdmin/win.xpl, which is what caused the crash, actually /does/, so I'm not sure if I can remove it or not. I'm not sure if I installed it with something else or if it was there to begin with (in which case I'll politely push back on LR since it was their code that crashed...)
Does anyone know?