1, maybe your WIN8 is not activated. You can go to some post bars to download the WIN8 activation tool, or buy the official activation code to activate. (Some activation tools may contain viruses. Pay attention to killing viruses after activation).
2. It may be caused by incorrect installation of the video card driver. Right-click the blank space of the desktop-adjust resolution-advanced settings-graphics driver-uninstall. Then open the toolbox in the lower right corner of Tencent's computer manager-find the hardware detection function, then install the driver, and search to install the graphics card driver.
3. It may be a theme problem. You can click Desktop-Computer-Control Panel-Change Personalized Settings-Change a theme you like.