I have an iPhone 4S and a MBP 2011 running the latest iTunes and Lion. My 4S is extremely unreliable when syncing over Wi-fi. Often the sync will time out and iTunes will give me an error "iPhone disk could not be found" even though it's on. Other times it will only sync half the songs on a new album, or will stall while trying to sync a large movie. Occasionally, the iPhone will just disappear from devices and won't show up at all! So frustrating. Anyone else having these problems and any suggestions?