coreldraw X6 (64-bit) has stopped working

CorelDraw X6 and PhotoPaint X6 are crashing on start-up (while the splash screen is present), with this message "CorelDraw X6 (64-bit) has stopped working" and "Corel PhotoPaint X6 (64-bit) has stopped working".

It was working fine a few weeks ago, but has since started doing this. I've gone back to a previous restore point and then re-installed the package several times, switching off everything I can think of, including my anti-virus package, but I get the same problem straight away - from the very first time I try to start CorelDraw or PhotoPaint. I am using Windows 7 Home Premium 64-bit. 

What should I do to get it working again?