i'm having exactly the same problem. I operate on a Windows 7 64 bit computer printing to an HP DesignJet Z3100 24" printer. this problem developed after I installed Photoshop CS6. My workaround is that I do not check the box in the print dialog for "Preview". However, I have always preferred to use preview to be sure the orientation is correct. I see in the HP User Guide at page 47 a note that "HP Print Preview is not available if you are using Adobe InDesign, Adobe Illustrator, Adobe Reader, or Apple Aperture." So I wonder if there is something in CS6 that causes print preview to become inoperable. Incidentally, after this problem occurred, I tried to print from CS5, and I have exactly the same issue. Previously, print preview worked fine from CS5.