Don't know why this issue has just cropped up recently (perhaps caused by a recent security update to Windows?). But we've seen two cases of this in the past week on 64 bit systems running Windows 7.

CorelDraw X3 contained a bug which prevented Postscript OpenType fonts from working properly (at all really). The flyout menu would just show a blank box where the sample text should be.

The solution is simply to download and install the latest patches from Corel's website. Once properly patched up, the version should read: 13.0.0.739 and the fonts will work fine.