When I sync my iPhone to my MacBook Pro I get the following error:

"Some of the items in the iTunes library, including [song name] were not copied to the iPhone [phone name] because they could not be found"

This always happens on the same single song and some podcasts.

Having searched many forums it appears that the reason is that the song may have been moved - however it hasn't. I can click on it in my iTunes library and it will play and the grey exclamation mark disappears.

If I sync again the problem doesn't occur.

However, once I disconnect my iPhone and then reconnect it, the problem re-occurs (although this doesn't happen 100% of the time - may require a couple of days to occur or a reboot).

Does anyone have any ideas?

Many thanks