Disappearing fonts...

Suddenly, none of the apps in the CorelDRAW 10 suite are handling certain fonts properly.

They show up on the font list in each app, but do not generate a preview when hovered over. If I change the font of a block of text to one of these fonts, the text disappears and the text box shrinks to an unmanageable size which cannot be resized. If I then change the font back to a working font the text reappears at its original size.

Typing a new block of text using any one of these effected fonts, the text cursor appears where I click but doesn't move as I type.

I've used these fonts for years with CD10 without a hitch. Even opening previous projects in which I used these fonts without issues, the text blocks are gone, replaced by the tiny blank text boxes I mentioned above (but the text will reappear if I change the font to an uneffected one).

I don't think there's anything wrong with the fonts themselves, as they still work in MS Word, Illustrator, and every other non-Corel product (except WordPerfect 8). I have both CD10 service packs installed. This happens on both my WinXP and Win7 pc's.

A Google search turned up only one result that sounded very similar to my issue. Applying the service packs worked for him, but I already have them installed.

I'm at a complete loss. Does anyone have any ideas...?