If you have tried iOS 5 beta, and now want to go back to iOS 4.3.x, you’ll need to downgrade iTunes too, from version 10.5 beta, back to version 10.3.x, which is currently being publicly offered by Apple.
Right alongside the release of iOS 5 beta 3, Apple has also seeded the third beta of iTunes 10.5 which is a major requirement if you plan on restoring your iPhone, iPad or iPod touch to iOS 5 beta 3.
