Editor's Note: This article, published in our August 2008 issue, includes information on .Mac, which will be replaced by MobileMe in early July. Any instructions may change significantly.
Syncing can be tricky business, and .Mac can need a helping hand to make it work the way you want. Perhaps the most common problem with .Mac Sync is that sometimes, even after repeated syncs, the data in one location still doesn’t match the other (and synchronization failures may not be accompanied by error messages). The first thing you should try if this problem arises is resetting your sync data—that is, erasing either the synchronized data on the .Mac servers or what’s on your Mac, and copying over it entirely with what’s on the other side.
To do so, go to the .Mac preference pane’s Sync tab, click on Advanced, and then click on Reset Sync Data. Choose All Sync Info (or a specific type of data if your problems involve just one) from the pop-up menu at the top of the window. Then click on either the left arrow (to erase the data currently on your Mac and replace it with what’s on .Mac) or the right arrow (to erase the data currently on .Mac and replace it with what’s on your Mac). Click on Replace. Repeat this entire procedure on each of the computers you sync with .Mac. But be careful to choose the correct arrow each time. For example, if your MacBook has correct data but your iMac doesn’t, you’ll first follow these steps on your MacBook, choosing to overwrite the information on .Mac with the information on your computer. Then when you reset your iMac, you’ll choose to overwrite its data with what’s on .Mac. Data will flow from one computer to .Mac to another computer—without getting jumbled in the process.
In rare cases, even resetting your .Mac data won’t solve sync problems. If this happens, go back to the .Mac pane’s Sync tab, click on Advanced, and select each computer in the list, one at a time, clicking on Unregister after each one and confirming that you do indeed want to unregister them. When you’ve unregistered your last computer, another window will appear, asking whether you’d like to delete unused information from .Mac. Put a check mark in each of this window’s check boxes, and click on Delete to completely erase your sync data from the .Mac servers. Then open iSync (in the Applications folder), choose iSync: Preferences, click on Reset Sync History, and confirm by again clicking on Reset Sync History; this erases all your sync data from your Mac. Finally, repeat the entire .Mac Sync setup process again, one computer at a time.