How far does it get when opening the disk image? Do you get the error message right away, or does the disk image opening dialog come up before the error appears? Also, could you attach a screenshot of the error (using the Grab utility, select Window as the object to grab, then click Select Window, then click the dialog to grab it. A save file dialog will appear - save the file as a TIFF, then open it in Preview and export it to PDF. After that's done, attach the PDF to a MacRumors post)?