Itunes asks to apply changes after sync but no changes have been made.

I had a problem with my old iPhone 3g where iTunes would ask to apply changes to my iPhone after I synced even though I hadn't made any changes. I didn't think much of it as I was awaiting the delivery of my new iPhone 4. Now the iPhone 4 has the same issue, every time I sync iTunes still wants to apply non existent changes. Does any body have any idea why this is and how to fix it. I have removed all the apps from the phone and this doesn't help.