This seems very strange. You haven't imported gedcoms that contain your data by any chance? If so, create a backup with a new name and then do an automatic merge based on unique serial numbers. See if it solves the problem.
If the PAF software has been damaged, uninstall it and then download and reinstall it. Note that the software is separate from your data. Still, it is good to save a backup on removable media from time to time. And before removing the PAF software would be a good time to do a backup. To backup to a CD, you will usually do a backup to the Desktop and then Copy or Send the backup to the CD.