Calendar App loads instead of MAIL

Calendar App loads instead of MAIL

When using one of the accounts associated to my domain, the EMAIL page NEVER LOADS.  Instead, the CALENDAR loads, and it loads without the app toolbar on the left hand side. so there is no way to link to mail.  For example, if I am on the page

https://home.zoho.com/home

and I click on the "Mail" icon

it takes me to the following page:

https://mail.zoho.com/biz/index.do

But instead of this page showing the email interface, it instead shows the Calendar.  The other accounts associated to this domain work correctly.  Only one of my email accounts does not.  It is as if the application defaults to the Calendar interface instead od the Mail interface. 

ANY SUGGESTIONS?  Solutions?