Prevent programs from locking Ctrl + Alt + Del
Solution 1:
Ctrl+Alt+Del is handled at the lowest level of the OS and cannot be overridden by user-space programs. This is why Windows requires Ctrl+Alt+Del before logon - this will ensure that the keys following the Ctrl+Alt+Del be handled by Windows and not other software.
Most likely your program that hangs has completely stopped the OS from running (e.g. causing memory/graphic card trouble and so on).