iOS 5 Beta 5 Syncing Problem

[CheatingSoi]

So I have iOS 5 beta 5 on my iPhone. My friend has a developers account and he added my phone to it. I was on beta 4 and then updated to beta 5. Now every time I restart my computer. iTunes detects my iPhone as a new one or something. It gives me the page to set up my iPhone and asks me to set it up as new or restore from backup. So every time i must restore from backup, losing the pictures ive taken and texts and it takes so much time. Is this a known problem? What can I do to fix this? I'm on iTunes 10.5 beta 5 as well.