Why do I have to continually sign in?

Why do I have to continually sign in?

Every time I return to Zoho, after having previously closed IE8, I have to sign in again.  The "Keep Me Signed In" box apparently no longer works for me..  It used to be that I could go directly to my inbox by clicking on Zoho in my favorites.   This is new.  My cookies are not removed automatically when I close IE8.  I also resaved Zoho in my favorites.
No change.
Thank you.