Repeated alert when using Zoho Sheet

Repeated alert when using Zoho Sheet

 When I open a sheet for some reason today I keep getting  a persistently repeating alert.  It's a modal dialog so it's extremely inconvenient, as I have to press the OK button, otherwise I am unable to do anything.

Here is a screenshot of the alert.

http://anroy.wiki.zoho.com/Sheet-Alert.html


Thanks.