You must have encountered this a lot of times. When your system suddenly stops responding and it hangs when you try and open a program. The best option left at such times is press Ctrl+Alt+Del at the same time on your keyboard and a dialog box titled "Windows Task Manager" will pop up. Once Windows Task Manager appears, you can bring back your system to normalcy without a hard reboot. Follow this tip: Press Ctrl + Alt + Del. "Windows Task Manager" will open. In "Windows Task Manager", under the "Processes" tab, click on "explorer.exe" once and then click on "End Process". All windows, including the icons on desktop will disappear except the Windows Task Manager. Next click, on the "File" menu on top and then click on "New Task". Here type: explorer.exe and lo, your system starts functioning just the way it was doing sometime back. Now you can reopen all the applications that closed earlier and resume your work.