My iPhone has stopped syncing with my mbp. It is driving me crazy. I have uninstalled iTunes, and restored my iPhone. When I try to re-sync my phone after doing all this the same problem: It shuts down after syncing about 3 songs. The songs don't make it to the phone! I think the calendar synced, and the contacts, but that is it. I was trying to put 25 songs on my 8GB iPhone, and there is plenty of room left, but it refuses to sync. There are no error messages or anything like that, it just stops working.
Call AppleCare or make appointment with Genius Bar near you (apple.com/retail). They are paid to solve problems under warranty.
Hold down the sleep / wake button and the home button until the screen turns off. Plug it into your macbook. Turn it on. See if it syncs. If it doesn't, try deselecting everything it syncs too. Like music, mail, calender, etc. Also, have you tried the manually add music feature?
I had a similar problem when I migrated an account to a new iMac. The iPhone either hung up on the sync and timed out or gave me an error code that made me think I was running Windows rather than OS X. The solution was to uncheck everything so that the iPhone was emptied out and then start incrementally resyncing the files. It turned out that the problem lay somewhere in the photo conversion so if I were to do it again I would start with the photo albums. Hope this helps and you find a solution to your problem.