how do i close a dialog box wehever i try to open a document in my e mail it keeps saying it can,t perform the command because a dialog box is open,
what is it and how do i get around this

A dialog box is just another term for a window that usually has some information directly related to something that is happening on your computer.

This could be another open window of your email client or a warning of something ....check the screen carefully for any minimized windows or behind the open window.