I'm doing a trial of Snow Leopard Server (10.6) running in a Parallels 12 VM hosted on MacOS Sierra (10.12). I found that whenever I try to open an image file (e.g. png, jpg, or tiff), Apple's Preview app displays a blank window for the image. The following error message appears numerous times in the console log Preview [xxx]: invalid pixel format Preview [xxx]: invalid contextPDF images seem to display properly with Preview. I haven't found anything that gives me a clue as to what I am doing wrong.