User cannot change selection in datagridview after selecting a cell with context menu

Question

I have a program that includes a DataGridView. One of the columns of the control has a context menu. The program replaces the value in the datagridview cell with the text of the item slected from the menu. This works fine, but once the user selects a cell in that column (whether the right mouse is clicked or not) the user can no longer select another cell. In fact the user cannot select any other control on the form

I have tried making the cell editable. I also tried clearing the selection. Neither helped. I would include some code but it is really all just generated in the .Designer module. Except for the code that actually updates the grid. That part works as expected.