It's not that frequent, but when it happens, it'll drive you up a wall.

In cases where your iPhone or iPod touch begins to sync with iTunes, only to drop out partway through the process and display a dialog box stating that the handheld has stopped working and the sync process has been canceled, Jeff Gamet over at The Mac Observer offers this workaround:

-Connect your iPhone or iPod touch to your Mac.
-After the sync process fails, launch iSync. You can find it in your Applications folder.
-Select iSync > Preferences.

-iSync is the key to restoring the sync process.
-Click the Reset Sync History button.
-iSync will display a dialog explaining what happens when you reset the sync history. -Go ahead and click the second Reset Sync History button.
-Quit iSync.

Keep in mind that your first post-reset sync may take longer than expected, but the function will be restored again.

If you've seen this kind of problem or found a workaround of your own, let us know over in the comments or forums.