Hello,
Since the latest updates of iTunes (10.6.0.40) and iOS (5.1) I am annoyed with a bug in the synch between my iPhone and my computer's iTunes.
Whenever I try to synch, iTunes get unresponsive when it arrives to synch the "Music". It would display "Choosing the tracks to synch" with the bar (with alternate white and gray bands) moving, indicating that it is working, but nothing happens even if I wait the whole night!
To make a work around, I uncheck the Synch Music box, make the synch which results in erasing all music from my iPhone. Then I check the same box again, make a synch, then it copies all my music from the computer to the iPhone one by one (consider the time involved!). The next time same chores.
I wonder if this happens to anyone of you. I am using Win7 64 bits.