We've just dealt with something similar recently. Xref-ed a file in AC9 with text looking fine one one computer, and weird squares on another computer. Didn't know what the problem was until I realized that we had just cleaned up the other computer and didn't have all the font files reinstalled yet. In our case it was the "country blueprint" font, or something like that.
So, make sure you have the proper font. Otherwise, see if you can map the font to a locally available font (don't know if PM can remap fonts on imports). If it doesn't work, try importing it through AC.
