I update iOS 4.0 with iTunes 9.2.
But, theme is suck caused by jailbreak.
So I decide to reinstall firmware for having mandatory theme style.
But, it failed reinstalling firmware several times even Restore only, not dfu.
So I try to install firmware again in itunes 9.1.1.
Then, restore backup from iTunes 9.2 which is before Jailbreak.
Yea, it's working.