Printing problem

I know, I THINK, what the problem is but don't know how to fix it.

I have a photograph of a student in Photoshop set to print. When I go to retrieve the print job from the printer, the portrait appears to be elongated, i.e., as if the picture was "squashed" to fit on the paper. I've set the margins to "zero"..ie. given the maximum amount of page space on the paper (printing to 8 1/2 X 11). I've tried landscape and portrait printing, but the result is the same.

I am getting a message prior to printing about the printer not recognizing postscript commands and some sort of adjustment is being made. That might be it...or...

It might have something to do with pixel aspect ratio (although I don't get a "warning" about that when the photo opens) but can't seem to find where in the menus to fix it.

What I'm trying to do is print out a photo of a student with a 1" X 1" grid on top so that the student can use it to draw a self-portrait in pencil.

Interestingly, when the picture is printed, the 1" X 1" grid is more like 3/4" X 3/4"...it too got squashed.

The picture looks great on the computer screen and even in the print preview, but crappy when printed out.

Any thoughts on what's happening?

Thanks,
John