Appointments disappear in iCal after converting from MobileMe to iCloud

Question

We recently converted to iCloud from Mobileme after upgrading to 10.7.2 and we have lost all of our appointments, both past and future in all calendars, both on the Macs and in iCloud.
When I first converted my machine, I had duplicate and triplicate entries, then after opening iCal for the third or fourth time, all entries dispapeared.  My wife experienced the same thing this morning.
Checked the "Hide" boxes and all are unticked.  If we add a new appointment, it will duplicate and/or disappear. 
I have an iPhone and the calendar is empty on that also.  My wife's Mac does not sync with an iPhone or any other device, just iCloud.
Any clues as to what is going on?

Answer 1

It took over an hour and three people, including second level support, but we have an answer.
Basically there is some confusion between the meta data being held on an external server (iCloud and/or Mobile Me) and the local machine.  Here's the SBS for the solution:
In System Preferences, uncheck all syncing in iCloud (pay attention to messages)
Logout of iCloud
Logout of Mobile Me
Sever the Internet connection, killing the connection to the external servers
Restore the Calendar data stored in user/library/calendar via Time Machine or other backup source
Open iCal and export all calendars to a backup location (user/documents will do)
Reconnect the Internet connection
Open System Preferences > iCloud, log back in to iCloud and re-establish syncing for all desired options, including Calendar
Open iCal and import backed up data
Check calendar for accuracy in iCal and iCloud