Well, here is my problem.
I have HP ProBook 455 G1 (AMD A4-4300M with AMD Radeon 7420G and dedicated AMD Radeon 8750M). Everything worked well until I reinstalled my OS, and tryed to install drivers for this graphics cards. When I tryed to install latest driver from official AMD driver website, my Device manager didn't show display devices (I first noticed that Windows Aero is disabled). The driver that I tryed to install is only for A4-4300M APU (and that is Catalyst 15.7.1 offered as latest for that component). The only solution I found was installing driver from HP's driver website for my laptop (Catalyst 15.201). And it worked as it should till I tryed to play games. Now, I can play games in Windowed mode, but not in Fullscreen.