I found the solution. My Laptop (Lenovo Y50) has two video cards: an Intel HD an Nvidia Gtx. So, with Intel Hd Rekordbox don't display well (and I don't know why). But with Nvidia all works correctly. How to configure it? (sorry if the menu's name ar not exactly)
Go to the Nvidia control panel -> 3d (configuration) -> add rekordbox program and select high performance nvidia procesor.