setContextMenu doesn't show the menu sporadically

[phonasoge]

v10.0p_2015-05-03/PowerEdition Deployment (built 2015-05-03)
While displaying ListGrid, we have setup a custom menu to be shown when right mouse button clicked.
The menu shows up and works correctly most of the time. Occasionally we've seen in IE11 where the
we get the default menu of IE instead of the one we have setup. When we reload the page, the problem
goes away. We are not getting any exception either. Any suggestions on how to debug this problem?

grid.addCellContextClickHandler(new CellContextClickHandler() {
public void onCellContextClick(final CellContextClickEvent rightClickEvent) {
Menu menu = new Menu(); ...
grid.setContextMenu(menu);
}
}

[phonasoge]

Any suggestions on how to handle the sporadic behavior in IE11? Appreciate a response.

[phonasoge]

we have paid for the support and the support plan state a guaranteed maximum response time of 3 days.