One of our engineers recently changed his MobileMe password and subsequently started having trouble with MobileMe syncing. It went away on its own, but it was very frustrating. It happened again today, and he decided to chat with MobileMe Support to see if he could get it fixed.
The Apple support technician said that it's a known bug and the MobileMe engineers are working to fix it. Until then the solution is the following:
- Open System Preferences and click on the MobileMe pane.
- Sign out of MobileMe.
- Sign in with a false username and password (type gibberish in both fields). This will give you the error that you have an incorrect username or password.
- Sign in with your correct username and password. All should work as expected.