The picture has frozen on one jigsaw, therefore cannot use the app.
This is just a bug in the application or an application error. It can be fixed by simply restarting the software and then continue from where you left off. If the software or the jigsaw is corrupted, avoid using it again and choose another image/level.
However, sometimes you can simply reinstall the software again through the following link: http://kraisoft.com/files/everydayjigsaw.exe