IE modal dialog Ajax Postback open a new window

Hi,

I have a asp.net web app using Ajax. A page opens a modal dialog window consisting a GridView control to list some data for user to select. When user clicks on column header, the dialog will postback and sort on that column.

This function works well in Chrome and Firefox. However, in IE 11, the postback will open a new window.

Is there any idea to resolve this?

Thanks.