My Dell Inspiron laptop with Windows 7 was working fine until yesterday evening. When I turn it on, it loads the Log In screen and I am able to type in my password and log in. However, after that I am presented with a black screen and a white cursor. It will not let me open Task Manager and when I press alt, ctrl and delete, after a few minutes I get this error message "Failure to display security and shut down options". I have tried System Restore but had no luck with that. I am not able to run in Safe Mode either, it constantly freezes. My laptop did not come with a Windows 7 operating CD.