I've run into the same problem too and I am using Firefox 36.0 Another problem I am having is that when I click week/day or month view the page loads fine but it's as if the whole calender has had the css opacity set to 0.5 or maybe even lower, the calendar is semi transparent. The only way to get the calendar looking normal is to refresh the page. I am using RC2
If you haven't already done so you need to purchase a domain name from a registrar. Then let Invision Power know what your domain is so they can set it up on their end. Then from your domain registrar point your domain to the nameservers Invision Power gives you.