Software like Roboform tends to support the Firefox Releases mainly and not the development channels like Beta, Aurora (deloper edition), and especially the unstable Nightly. Nightly and Aurora channel gets checkins almost everyday so therefore there is a update each of those days. Sometimes the checkin(s) can cause issues or changes in various ways until fixed or reverted unless it was intended. The Beta and Aurora channel has Win64 builds in case that is reason why you are Testing the Nightly builds. www.mozilla.org/beta/