This issue, as far as I can see, is totally GUI based. I don't think you need any code to re-create it.
When there is a column (or two) in the "group by" panel, and you hold and slightly move one of the columns, but not enough to actually change the grouping, one of the group header's text will be cleared. In my case I have used the AutoGenerateColumns feature along with SaveLayout and LoadLayout. I am on Windows Vista. Even in this example application (for a different thing), the issue is still shown.
When there is a column (or two) in the "group by" panel, and you hold and slightly move one of the columns, but not enough to actually change the grouping, one of the group header's text will be cleared. In my case I have used the AutoGenerateColumns feature along with SaveLayout and LoadLayout. I am on Windows Vista. Even in this example application (for a different thing), the issue is still shown.