Data not displayed, GIves Processing please wait

Hi,
I have installed simpleinvoices and i am able to enter data also. But the display is not working. It gets stuck showing : processing please wait
I checked with the firebug console also. The post is getting back data and I am able to see the data. But it is not being rendered.

Also if I keep authentication.enabled as true, it blanks out. If I set display errors on it gives headers already sent by NumToWord.class.php in auth/auth.php