FW Batch destroys my pictures!!!

When converting a vertikal picture from 350DPI to 150DPI (yes i checkmark in
manually it works as intended but when i batch process pictures this way it
stretches the vertical pictures (not the horisontal ones) by 40%. (reducing
them to 60% makes them look sort of normal sized again)

and furthermore - it ALSO destroys the backups it makes!!!!

:-(