Irreversible Stretch?

Irreversible Stretch?
Often while modeling small projects a key combination of some sort seems to destroy my whole project. When using some key combo on the left side of my keyboard my fingers must slip causing an unwanted affect. Suddenly my whole model stretches into one long string that can not be manipulated. When I try to ‘Undo’ the action, nothing happens. What is it? How can it be undone or avoided?

can you post a screenshot?

double post…blenderartist seems a little quirky lately…