If the Drive E is an external removable drive, then that could happen when it is disconnected or powered down without first using the Safely remove hardware button to let one know when it can safely be removed. I would save the project files (.pds) in the Documents\Cyberlink\PowerDirector\18.0\ internal drive folder for all projects while the assets, import, and produced folders can be kept in the external drive. This would lessen the chance of the .pds file not being completely written to disk. You may also save your projects using save as… with a suffix of say -1, -2, -3, and so on in case the last one gets corrupted again. You would then have a previous one to use.