I should have been more clear. The windows ntfs, corrupt filesystem errors appear only when the iPhone is plugged in. The disk with the ntfs corrupt filesystem is harddisk2 - the iPhone (OS is on harddisk0).
The iPhone owner isn't technical, they might be plugging something else in and not realize it but they swear to me the only device they ever plug in is the iPhone.
I mentioned the errors to him as a heads up that a USB stick or external drive he is using needs attention. He responded that the only device he plugs in is the iPhone.
Thanks,