Win7 The task Manager can't get it out.

First press Ctrl+shift+esc to see if you can pull up Task Manager, if not, first check the System Group Policy settings are problematic: in the Group Policy Editor, find "User configuration → administrative Templates → system →ctrl+alt+dele options", found on the left "delete Task Manager" , and change it directly to "Not configured." If it still doesn't work, the system file may be Taskmgr.exe, and you can search for the file from other versions of the operating system (by default under C:windowssystem32) and copy it to your system's folder of the same name.