Thanks Betty. It could be the problem although I have now sorted it out by deleting the DNG software and installing the latest version 9. The hardest part was finding where Windows had hidden the DNG Converter software (not in Control Panel>Programmes) Eventually found it, deleted it and installed Version 9. All is well. But to get back to your suggestion. I recently replaced my old/faulty monitor with another one of higher resolution, so that could be it, although I can't be sure as DNG Converter isn't something I use every week.