One of the problems that you encounter if you use Windows 7 regards the sudden appearance of a black screen that looks not only at boot time but once you get to the login screen. In total darkness, if you enter username and password will be able to come in Windows 7 because you will hear the classic sound of a login but the screen will remain black. So how to solve? You do not need to force format but you can try to resume it by following these steps.
Once in the system (always with a black screen) if it works try the key combination CTRL+ALT+DEL. If not, use the combination Windows_key+L to stop the session and now press CTRL+ALT+DEL. Access to "management tasks" The board "Applications" Selected "New Task" And type in explorer.exe! You should be able to magically re-enter the system.
Now you have to understand what the problem may have been the updating of Windows 7 SP1, a video driver installed, a firewall or antivirus. In any case, you have to go to attempts but, the problem is related to 'installing the latest version of ZoneAlarm: You can just uninstall it and you will not have any problem.