Google Calendar HTML View - Broken?

Google Calendar HTML View - Broken?

For over a year I have had  a link to a Google calendar embedded in an HTML view (so that the users can see their Google Calendar within my Zoho Creator App).  All of a sudden this appears to be broken.  In Firefox this will just not display and in IE8 I am getting the error "this content cannot be displayed in a frame".

Is this a Zoho issue or a Google issue?  Is there any way to resolve this?