I have been using MobileMe since 2006. I have never had a problem syncing MobileMe to my MacBook but now I have a iMac and an iPhone. I have to problems syncing MobileMe, iPhone and MacBook together, every change made in either devices will show up on the other. The problem is on my iMac where iCal syncs 100% accurate with any changes or updates made from either iPHone or MacBook or MobileMe but my Contacts will not sync at all. I have turned sync on/off many times, registered and re-registered the iMac with MobileMe many times, double and tripled checked the Address Book preferences (making sure 'Sync with MobielMe' is checked) and even exported vCards from MobileMe and imported them into Address Book and then added at 'test' contact from my iPhone to see if after syncing it would show up on the iMac and it didn't (but it did show on my MacBook and MobileMe). I also tried adding a 'test' event from my iPhone and that was updated after syncing and all devices. Clearly Address Book is the only app not syncing anything at all and it only happens on the iMac. Both Contact syncing on MacBook and iPhone work great. Please help!