OK...I am not going to explain this too well, but every now and then the internet...err..stops, unless I move my mouse around.
To try and make that make more sense...adverts and smilies etc will stop moving and pages will not load or update...unless...I move the mouse around on my screen.
The internet is mouse powered, like those wrist watches that are powered by regular movement of your wrist, the internet runs on power generated by everyone moving their mouse.