Sometimes, the cursor keys stop to work: The cursor suddenly does not move any more when I press these keys. When I then click somewhere in the window using the mouse cursor, the keys work for a time.
Besides that, I cannot read a page on my smartphone using the Firefox app, since I can only read a single screen: It is permanently scrolling back when I scroll manually.
Since this behavior is so striking and a showstopper, I am almost surely doing something wrong. Do you have an idea what that could be?