Apple is aware that some third-parties claim that their digital media players are able to sync with Apple software. However, Apple does not provide support for, or test for compatibility with, non-Apple digital media players and, because software changes over time, newer versions of Apple’s iTunes software may no longer provide syncing functionality with non-Apple digital media players.
Hope you have a chance to back everything up. Like I said earlier, this could have all been avoided had Palm simply updated Palm Desktop to work with the Pre.
(from this Apple Support Page)