Cancelling a program launch

[Sebastian42]

What keystroke or technique will cancel an UNWANTED launch that has started ?

[Fruss Tray Ted]

Three finger salute (CTRL, Alt, Del) and end process?

It depends what is installing and how far it has gotten as well because you may end up with an unusable system in need of a reinstall.

[Sylvander]

If you download/install/run Process Explorer (http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx), you can terminate/kill individual processes, or the whole process tree.

Check whether it can run OK on your version of Windows.

[Paul Komski]

Not quite what was asked but ALT+F4 closes the active Window.