It could be a bug or incompatibility in one of the many many updates of the browser or ....
In the automatic mode, that doesn't stop. Everyday new something comes and had to be loaded, new stuff, repair, correction of bugs, correction of the correction... And all in our back, we can't master any of that at all (me at least). It's a black box, I hate that.
At a moment, it was unbearable. Every 2 or 3 updates of my windows xp, my computer crashed, basically "new stuff wrong". A day when it worked correctly, I shut down the automatic upload, way better like that.