We are also getting the same error. This is our situation and how it
manifests:
Our web application uses an asp.net 2.0 menu and sitemap for navigation.
The page has an asp.net 2.0 treeview control on it. The data in the tree
view is built on the fly. A dhtml behavior is used to keep the selected item
in the treeview in about the middle of the screen(vertically). An Iframe is
used to display information about the item selected in the treeview or pages
selected from the menu.
the menu behaves as expected until the following conditions are met:
1 the mouse has been passed over the menu,
2 any item on the treeview is selected or expanded.
3 the mouse is pased over the menu again
We have noticed that the menu repositions itself 3px to the right of the
original position just before the above problem manifests.
The menu's will all drop down and will not disappear until the next
postback. The menu's will continue to lock down if the mouse is passed over
them until the page is refreshed.
The client scripting error that appears is "0.Cells is null or not an object"
Here is the page aspx:
<asp

anel id="PanelMenu" style="width: 840px; position: absolute; top:
64px; z-index: 5; left: 101px; height: 15px; background-color: transparent;"
runat="server">
<asp:menu id="MenuHSNOCertifications" runat="server"
datasourceid="SiteMapDataSource1" orientation="Horizontal"
staticdisplaylevels="2" style="z-index: 1; position: absolute;"
disappearafter="-1" enabletheming="False">
<staticmenustyle backcolor="Transparent" bordercolor="#739574"
horizontalpadding="5px" borderstyle="None" borderwidth="1px"
cssclass="HSNOMenu" />
<staticmenuitemstyle cssclass="HSNOMenu" />
<dynamicmenustyle backcolor="Transparent" bordercolor="#739574"
borderstyle="Dotted" borderwidth="1px" cssclass="HSNOMenu" />
<dynamicmenuitemstyle horizontalpadding="10px"
verticalpadding="2px" cssclass="HSNOMenu" />
<statichoverstyle backcolor="White" font-underline="True"
cssclass="HSNOMenu" />
<dynamichoverstyle cssclass="HSNOMenu" font-underline="True" />
<staticselectedstyle cssclass="HSNOMenu" />
<dynamicselectedstyle cssclass="HSNOMenu" />
</asp:menu>
<asp:sitemapdatasource id="SiteMapDataSource1" runat="server" />
</asp

anel>
<asp:TreeView ID="TreeViewHSNOLocations" runat="server"
NodeIndent="5" AutoGenerateDataBindings="false" EnableTheming="false"
PopulateNodesFromClient="False" style="width: 240px; height: 520px; z-index:
1; position: absolute; top:97px; left:10px;" nodewrap="True"
cssclass="ScrollingPanel" enableclientscript="False">
<hovernodestyle forecolor="CadetBlue" />
<selectednodestyle forecolor="Blue" />
</asp:TreeView>
<iframe id="FrameRight" name="FrameRight" runat="server" scrolling="no"
style="position:absolute; top:100px; left:256px; width:724px; height: 520px;
background-color: transparent; z-index: 3;" frameborder="0"></iframe>
Thanks in advance