I installed iOS 5 beta 4 on my iPhone 4 using iTunes 10.5 beta 4 without an issue. I backed up my phone before upgrading iTunes and my phone with iTunes 10.4. After upgrading both iTunes and iPhone I attempt to do a restore but receive an error message saying that "This version of iTunes is too old to sync". I am able to restore all of my contacts with iTunes but it does not allow me to restore music, ringtones or applications. If someone has a solution or method of downgrading iTunes to an earlier beta or any other options let me know!