In Star Wars: Knights of the Old Republic, we learn that long before the original Republic, the galaxy was ruled by the Builder Empire, an oppressive regime of dark-side Rakata who used the dark side of the force to power enormous weapons like the Star Forge, a prism of malice that dwarfs the Death Star. But the Builders were undone when their race was swept with a mysterious plague that stripped them of their Force powers and left them unable to command their war machines.
Is the origin of the plague ever explained? I don't recall hearing one in either Old Republic games. Nor do I know of any extended universe fiction that delves into the matter. Does anyone know of any explanation?
Personally I like to imagine the plague being generated reflexively by the Force in resistance to the Builders' abuse of it - much as in the way it resisted Darth Plagueis - but if a non-speculative explanation exists I'd love to hear it!