CAUSE:

- The DIV contained an UpdatePanel with the id “MultiView”. Inside the
ContentTemplate of the UpdatePanel there was a asp:menu Control.
- The Menu Control has these items:
<Items>
<asp:MenuItem Text="Notes" Value="0" ></asp:MenuItem>
<asp:MenuItem Text="Attachment" Value="1"></asp:MenuItem>
<asp:MenuItem Text="Histroy" Value="2"></asp:MenuItem>
</Items>

- Upon Clicking on any of the above three Menu items , we get “0.cells is null or
not an element” .
- Since the menu Control is not supported in a Partial page Update Scenario , We
will not be able to make the asp:menu control work from
within an UpdatePanel.

WORK AROUND:
The only workaround is to remove the asp:menu Control from within the
ContentTemplate of the UpdatePanel.

- Further reference about controls compatible with the UpdatePanel .
http://www.asp.net/ajax/documentation/live/overview/UpdatePanelOverview.aspx