If you haven't already tried it, I suggest that you restart your computer. Sometimes PAF's printing routines get confused, and rebooting the computer solves the problem.(Fortunately this problem seems to be limited to printing routines.)
Another possibility is that the link between the photos and the database has been broken. The most common reasonis that the photos or database have been moved. (Keep them in the same folder to allow them to be moved to another computer or another location without breaking the links.) This problem is easily corrected, by linking one person in the database to the appropriate photo and agreeing when PAF asks if you want to use that folder for all other photos. (If the PAF photos are not in the same folder, this problem was inevitable.)
A third possibility is that the photos have been converted to an image format that PAF doesn't recognize. This is very unlikely, but I have at least one graphics program on my computer that could do this. Check to see what the extension is on the names of the photos. If it is anything other than JPG/JPEG, PNG, BMP or possibly TIF, you will need to convert them back (JPG is most efficient).
Let us know if you were able to solve the problem.