Hi all,
I believe I have found a number of issues regarding the 10.2 with iPad/iPhone syncing with the 4.2.1. I was experiencing breaks in syncing my iPad on 4.2.1 to the iTunes 10.2.1 and I resolved it with the following methods:
a)Reinstall with iTunes Installer (not from Software Update) - it seems the one from Software Update is buggy, so replace it.
b) Connect directly to your Mac or PC on USB without use of a hub, as some hubs cause connection issues.
c) Delete the temp data (not your iPad/iPod folder) in user/Library/Logs/CrashReporter/MobileDevice/TheNameOfYouriPod/ (for Mac) and C:\Users\YourUserName\AppData\Roaming\Apple Computer\Logs\CrashReporter\MobileDevice\iPodName\ for Windows Vista
d) If using Windows install Windows SP1 and reinstall iTunes. This will help with USB connection issues >
http://forums.mydigitallife.info/threads/24666-The-Windows-7-SP1-USB-Driver-Bug-(what-it-is-and-how-to-fix-it)
e) Delete the iPod Photo Cache.
f) Uncheck the Sync with iPhoto on iTunes.
g) Change your USB cable.
h) If further problems delete apps that download mags to be read - these use up lots of space.
i) Also if you have copied over any RAW or DNG image files inadvertently into your iPad these may be your primary cause of conflict with the syncing.