When psp crashes or freezes for some reason and you haven't saved your work, you can lose everything...:(
Go to FILE, PREFERANCES, AUTOSAVE settings.
This will open the Autosave Settings dialogue box.
Tick the "enable autosave" box. Set the time schedule you need, 5 min. should be sufficient. Click ok. Autosave is now enabled and your work will automatically be saved to the temp file every 5 min. If psp crashes you can re-open and your work will be loaded as before...:)