I was able to create a beautiful wallpaper, but after this first one, Wallpaperio crashes when I click "Preview" or "Save wallpaper". My OS is Mac 10.5.7.
Thanks for any advice.
You don't necessarily need your disks. From the Finder, press the keys command + shift + U together at once to bring up the utilities folder. Click on "Disk Utility" to verify and repair your permissions.