iphone calendar is frozen, crashes constantly

I use my iphone calendar ALL the time. I used it most the day today without problem. All the sudden, though, now when I go into the calendar, it won't let me do anything. It just freezes and eventually crashes back to the home screen. Sometimes when I first get into the calendar, it will let me click one item or scroll a couple of lines (in list mode), but beyond that, it won't budge. Haven't been able to get back to month mode, add or delete any items, nothing. The last couple of times it hasn't even let me do anything.

I have rebooted the phone three times and will try to sync it tonight, but I don't know what good that will do, if anything. This is VERY frusrating as I use my calendar throughout the day every day.

I have it synched with my google calendar if that makes any difference.

Any ideas?
TIA!