Sony tries to pretend the bug doesn't exist, because if you use their software for conversion, you'll never notice it. So it's not a bug, right? It's just incompatibility with ebooks built by other people!

Which, um, every other epub reader on the planet can handle.

(Sony's bug comes from the hardware limitations of the PRS-500; limiting the files to 300kb pieces was a way to keep long files from taking forever to load. We have faster processors now.)