Question Details: My friend cannot open an attachment because when he clicks on it, it says cannot open because a dialog box is open.

Answer

A dialog box is a rectangular box that either requests or provides information. Many dialog boxes present options to choose from before Windows can carry out a command. Some dialog boxes present warnings or explain why a command can't be completed.

You should look for opened dialog boxes on your computer and close them before trying to open the attachement. To close a dialog boxe try to click on the red X in the right corner of the dialog box.