This happened using DataGrid v 4.2.11480.14340.

1.) Loading up a bunch of data using DataGridVirtualizingCollectionView
2.) Add a grouping for one of the columns
3.) Expand the grouping

That's when we saw this crash. He may have selected a row (not sure), but it was before the data had become loaded. 

Hi John, 

Could you send us a sample application that demonstrates this issue so that we investigate this in more detail and provide you with a better answer?

You could send it to support@xceed.com . Please include a reference to this forum post in your email.