I had also installed Windows 7 and till this morning everything goes well. The operating system loads after the start of the session instead of going on the desktop nothing happened. There was just a black screen. I can just move my mouse that I see the white cursor and arrow, but that's all. I press Ctrl + Alt + Del but the same does not work at all. So I started the PC in safe mode with network support. I have Nvidia driver. What should I do here.