This is really pain and didn't good for me.
Why my Wallpaper reseted each time I restart my MacBook Pro? This is not just resetted but also all my wallpaper configuration set back to the default setting.
Any guide how to permanently fix it?
Back up all data.
Boot from your recovery partition by holding down the key combination command-R at the startup chime. Release the keys when you see a gray screen with a spinning dial.
When the Recovery desktop appears, reinstall the Mac OS. You don't need to erase the boot volume, and you won't need your backup unless something goes wrong. If your Mac didn’t ship with Lion, you’ll need the Apple ID and password you used to upgrade, so make a note of those before you begin.