Segue abaixo direto do suporte Apple - EUA, como "resetar" a configuração para fazer funcionar tudo normal novamente, sincronizando MobileMe, MAC (iMac, Macbook) e iphone.
Basta seguir passo a passo que da certinho:
Patrick C: what does the error message say?
it says (translating from portuguese BR): Calendar (iCal) could not sync due to inconsistent data
Patrick C: Alright, we are going to have to perform a calendar reset
Patrick C: We will need to sync through iTunes then to bring your events over, and then reset up
Patrick C: On your iPhone, click on Settings > mail, contacts, calendars
Patrick C: Click on your MobileMe account here
Patrick C: locate the Calendar slider, and slide this to "Off" and choose "Keep data on iPhone"
Patrick C: On your mac, open up your system preferences > MobileMe
Patrick C: and click on Sign Out
Patrick C: Plug your iPHone into your Mac
Patrick C: and cancel the sync as soon as it initiates
Patrick C: To sign out, click on the Apple icon at the top left of your screen
Patrick C: Click on System Preferences from the drop down
Patrick C: Then click on the MobileMe icon here
Patrick C: And click on Sign Out
Patrick C: At the top left of your screen, do you see the Apple icon?
Patrick C: Click on that
Patrick C: Let me know if you see System Preferences from the drop down
Patrick C: Click on that
Patrick C: Then let me know if you see a MobileMe icon here
Patrick C: Click on that
Patrick C: a small box will open up
Patrick C: Click on Sign Out there
Patrick C: Plug your iPhone into your Mac
Patrick C: cancel the sync as soon as it starts
Patrick C: In iTunes, locate "Devices" in the left-hand sidebar
Patrick C: Click on your iPHone here
Patrick C: and then click on the Info tab.
Patrick C: Uncheck everything here
Patrick C: and then check mark "Sync Calendars"
Patrick C: Click on Apply.
Patrick C: Yes, it can take some time for this to finish
Patrick C: Alright, yes, when syncing through iTunes, it can take awhile as it will need to back up your data and then sync it over to your computer.
Patrick C: Once your iTunes sync finishes, unplug your iPHone
Patrick C: Ensure your calendars now show up in iCal
Patrick C: Click on File > Back up iCal and save a copy to your desktop (Always good to have a backup)
Patrick C: Then open up your System Preferences > MobileMe
Patrick C: SIgn back in here
Patrick C: Then click on the Sync tab.
Patrick C: Place a check mark next to "Sync with MobileMe" and select "Use Same Name" when prompted.
Patrick C: Then place a check mark next to "Calendars"
Patrick C: CLick on Sync Now, once prompted, select "replace on MobileMe"
Patrick C: This will clear up that inconsistent data issue.
Patrick C: Then you can recheck the rest of your data and set your Sync with MobileMe to AUtomatically.
Patrick C: After the iTunes sync has finished you will want to open up iCal and make sure the iPhone calendars show up in your ical application
Patrick C: Great, and thank you for your patience throughout this
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