I'm waiting for a response to this thread from intersoft support. It's been over a week since I posted the question. Is there a phone number or some way to contact support directly or escalate an issue?

Apologize for the delay in sending this.

I tried to replicate the reported problem in my local end by modifying HierarchicalGrid.aspx sample file of WebGrid. Based on your information, more columns were added in the root table. It has 33 columns after modified.

Detail of the steps to reproduce is as follow:

1. Save changes and view the page in IE 9 browser (using IE 11 emulation by setting document mode to IE9 and user agent string to IE9).
2. Try to expand child table.
3. Try to scroll horizontally and/or vertically.

Unfortunately my efforts were not successful. Doing the above steps doesn't causing IE 9 browser to freeze.

For your information, I'm using the latest version of WebGrid 9. Please feel free to let me know if you find anything that I might miss during my attempt to reproduce the problem.

My grid config is:

<ISWebGrid:WebGrid id="_grid" runat="server">
<RootTable DataKeyField="xNodeID" DataMember="HierarchySummaryM">
<SelfReferencingSettings
Enabled="true"
ChildDataMember="xParentNodeID"
ParentDataMember="xNodeID"
ExpandColumnMember="xNodeDescription"
/>
</RootTable>
<LayoutSettings>
<ClientSideEvents OnRowContextMenu="trees.onGridContextMenu" OnAfterResponseProcess="trees.onAfterResponseProcess" />
</LayoutSettings>
<FlyPostBackSettings PostInputControls="true" />
</ISWebGrid:WebGrid>

On the InitializeLayout event, I have:

I modified SelfReferencingGrid.aspx sample based on your snippet code. The sample is enclosed as attachment. Save the changes and view the page in IE 9.

I was unable to replicate the problem. Rendering and expand child row run without any issues. Please check the video which shows how the test was conducted in my local end and feel free to let me know if you find anything that I might miss during my attempt to reproduce the problem.