iCal stuck upgrading calendars

I just upgraded from Lion to Mountain Lion and opened up iCal to see it said it had to upgrade the calendars. The progress isn't even 1/8th complete and just lingers there. I can't quit the program like normal and when I go to force quit, it lists iCal there like normal vs. "not responding," yet no progress is being made.

I tried opening the app package contents and deleting the info.plist file in hope that re-opening iCal may reset itself, but it didn't even launch when I clicked on it. I even tried rebooting with the plist file in the trash and iCal still wouldn't launch. Is there another file I can delete that will force a reset on iCal or is there a way through Command Line that I can do it?

I've read of other similar issues but on Lion.

Any ideas?