I have 2 questions for a 4S
Everytime I sync my 4S it resync's 200-300 songs when there was no change.
2nd question, is if I sync a lot of new songs ITunes will always crash, anyone have an ideas?
Make sure itunes is up to date, if you are using a Windows pc and iTunes is already up to date then uninstall iTunes and all its components by follow the steps in the artcile below then download a fresh new version then install it.
Windows XP
http://support.apple.com/kb/ht1925
Windows Vista/7
http://support.apple.com/kb/HT1923