Text disappears in the Viewer
Problem
Your presentation looks perfect when you view it in PowerPoint but when you or others view it using the free PowerPoint Viewer, some or all of the text disappears.
The same thing might happen when you Package For CD and view the packaged presentation, since it launches in the Viewer as well.
Solution
The problem may be due to minor corruption in the original PowerPoint file.
To fix it, try round-tripping the file to HTML and back. You'll find instructions here: HTML "Round-tripping" to repair corruption.
Round-tripping works in PowerPoint 2000 and up but may not be fully functional in PowerPoint 2007.
NEVER round-trip your original presentation file. ALWAYS work on a copy.