Seems to happen when you change devices.
I am running Snow Leopard and have Itunes 10.6.3 and IOS 5.1.1 Iphone 4, yesterday I plugged in my phone and itunes poped up and says" this computer has been previously synced with an Iphone or other iOS device" this is my personal computer and no one has synced it and I lasted syned my phone August 23th.
Its now asking me to setup a new phone or restore from the August 23rd , I tried restarting but nothing happened so I resorted to clicking restore from last back up and after 20 min of restoring it still shows setup as new phone or restore ( I tried it twice) after I plug in my phone
I have also upgraded to Itunes 10.7 but still face the same problem.
any idea guys and any help is appreciated