This worked for me too, or appears almost certain to work since my phone is still rebooting as I type. Typically I keep most of my Nandroid backups on my notebook PC, where I rename them so I'll have a clue as to what the status of my phone was when making the backup--e.g.2012-12-28.06.15.27 Hydro with apps. Whether this will fix my issue with the Google calendar I don't know but I will definitely be sure to thank the poster who provided this very helpful information.
I'd like to thank the person over at XDA too, but I can't post there.
ETA: This also fixed the calendar issue I was having, the one where you get there error message that the process.com.android.calendar task has stopped running unexpectedly. That was the original reason I wanted to restore from Nandroid in the first place.