I cannot get iCal to STOP emailing!

I do not have Mail installed on my MBP (snow leopard). I have iCal working just fine and it is syncing with my google calendar. However, every time an even pops up iCal wants to load up Mail to send an invite or reminder or something. And then I just get this warning that Mail cannot be found and I have to Force Quit it. This happens for every even but I cannot find a place to turn this off.

Any help is greatly appreciated.

Regards,
SF