Why did the background image reload when the mouse is over a menu item?
— The problem happened when you chose “every visit to the page” in settings of internet temporary files of the Internet Option. In this case, when you mouse over the menu item, the browser will check the new version of the page and reload it as well as the images. In fact, the default setting there should be “Automatically” rather than “every visit to the page”. Thus, the problem will not exist.
