I am running the latest version of all software on my Windows 7 machine iPhone 4S and iPad 2. I leave iTunes running all the time for wifi sync. I am finding that the wifi sync is very hit or miss (mostly miss) It seems like nearly every time I try to wifi sync it fails. I will move over to my Windows 7 machine there will be an error in iTunes saying either "iPhone could not be synced because the required disk could not be found" or "iPhone could not be synced because of an unknown error" at this point I will usually have to force quit iTunes though the task manager. Once iTunes comes back up wifi sync will work fine for a short period of time.