About a week ago iTunes began crashing each time I synced my iPhone. Initially it happened right at the end of the sync and so, although irritating, it was possible to ignore it while simultaneously searching for a solution online. The problem started immediately after I had installed the new version of Google Earth and so my initial thoughts were that it was in some way related to a change that had been made as part of that install. But uninstalling Google Earth had no effect.
The nature of the problem was that the more I ignored it the further forward in the sync process it got until eventually iTunes would crash immediately on recognising the iPhone and display the "iTunes has stopped working" popup.
The Apple support forums were of little help. They seemed to contain little in the way of advice from Apple and a lot in the way of posts from similar and confused iTunes users who were experiencing similar problems to me.
One apparently useful suggestion from the forums was that the issue might be resolved by uninstalling QuickTime and then re-installing iTunes+QuickTime together. This had no effect either.
Following another line of hope I performed a restore on the iPhone which reloads the firmware and attempts to recover the iPhone settings from the most recent backup. Again, no solution.
After a number of frustrating evenings of tinkering I stumbled on the solution that worked for me: From the iTunes store menu choose "Deauthorize Computer…" followed by "Authorize Computer…". I have no idea why that solved the problem but I can now sync again and if you have stumbled upon this post because you have the same problem I really hope it works for you.
I can’t understand how Apple can produce such a wonderful user experience on the iPhone and Apple TV and such an awful one on iTunes and the Apple support web site.