ical has a problem opening

Lately, every time I open iCal it shows up with a problem report for iCal. It specifically says, "iCal quit unexpectedly." I seem to be getting this every time I try to use iCal.

There is a report being sent to Apple every time this happens but I don't know why it's happening and would like for it to stop.

Now, I can't even access iCal because it goes into this loop of reopening and the error!

I need some help.