Just in the last couple of weeks everytime I try to synch my iPhone 5s to my Mac it wants to resynch EVERY SINGLE TUNE in the library. Often when I start the synch the capacity bar in iTunes show that I've 50+GB free before it suddenly jumps up to the real capacity of only 5 or so GB free then it starts to copy all 7,000+ tunes. I let it do this once (took a day) last week but now it wants to do it again... serious wtf!!! Anyone have any advice about what's going on here??? And more importantly how to fix it?