Purchased Fonts Not Displaying in PowerPoint?
By Paula Tesch
We had the same problem! It wreaked a bit of havoc before The PowerPoint® Blog released a fix.
Turns out, a recent security update caused Open Type fonts not to display in PowerPoint. The fine folks at the PowerPoint® Blog identified the problem (Microsoft Security Update KB2753842) and a offered a solution (remove it.)
All the info you need is here.