With CTRL+ALT+DEL you invoke the Team Monitor which lists all currently running programs.

Programs that were launched by the system are blue, those started by the user black.
Applications that are unresponsive, which is often a sign the program has crashed, are marked red. You can kill a program by selecting it and pressing the Kill Application button.

You can summon a Terminal with ALT+SHIFT+T.

If your Tracker or Deskbar crashed or froze, a new button appears (you may have to kill the offending team first): Restart the Desktop will restart Tracker and/or Deskbar for you.