We hit this technical support question recently, and thought others might like to be aware of it. One of our SBL Hebrew users reported that his existing Powerpoint documents were broken when he updated to the latest version of the font, despite the fact that the font works correctly elsewhere and he can also create new Powerpoint documents correctly. It turns out that Powerpoint stores glyphs by glyph index in slide/preview mode, and will not automatically refresh if you install a new version of the font with different glyph ordering. Thankfully, there is an easy fix for this one: the user has to open each slide of the document in edit mode (by double-clicking on it). This will refresh the glyph display.

So if you are providing updates to fonts that include changes to the glyph set indexing you might want to alert Powerpoint users that they will need to refresh their documents. I can imagine a user getting very upset if he stood up infront of an audience to give a presentation only to find all his slides broken because he installed a new font or was running his presentation from a machine that had a different version of the font.