.mac not syncing with Address Book?

Try resetting .Mac sync data

to reset sync information:
1) Open System Preferences and click .Mac.
2) Click Advanced and then click Reset Sync Data.
3) Choose the information you want to reset from the Replace pop-up menu (such as Bookmarks, Contacts, or All Sync Info).
4) Click the right arrow. The screen will change to say "On .Mac with sync info from this computer."
5) Click Replace. This will replace the information on .Mac with the information from your computer.

after resetting your sync information, you may need to reset your .Mac Bookmarks if you sync those.

1) Go to .Mac http://www.mac.com and log in.
2) Click Address Book and then click Preferences.
3) Deselect the "Turn on .Mac Address Book Synchronization" checkbox, and click Save.
4) Click Preferences again, reselect the checkbox, and click Save.

Of that doesn't work you can always try writing the dot mac support team an email. sadly there is customer service support center.