stretching can occur if you're using a background image instead of actual objects... or in P5, if you don't select "match document window" first, and make sure constrain aspect ratio is checked...then you can change the size without LOSING information...I've never seen distortion/stretching otherwise...

Humankind has not woven the web of life. We are but one thread within it.
Whatever we do to the web, we do to ourselves. All things are bound together.
All things connect......Chief Seattle, 1854