Hi,
I'm having the same problem occasionally. It happens when I try to select some lines using a ctrl-shift-arrow combination. The text gets right-aligned if I press the right-ctrl and right-shift key together. To correct it, I can press the left-ctrl and left-shift key together.
I guess it has something to do with right-to-left languages, but haven't found a way yet (in Designer or Windows 7) to disable it.
Mark