Sorry to bring an old post back from the dead, but I was having this same issue and found this thread. I cannot beleive that I am still seeing this issue (Explorer windows opened after AutoCAD has been started flicker on form hide) in AutoCAD 2011!
As someone mentioned, this does not occur if the windows are minimized first.
i came across this thread while i was trying to solve a similar problem
I have a modal form, that shows a new modal form in a button.click event handler
Private Sub MyButton_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyButton.Click Me.Hide() Dim modalForm As New MyForm() AcApp.ShowModalDialog(modalForm) Me.Show() End Sub
after MyForm is showed, i see it's window and the background is not AutoCAD, but any application that was focused before AutoCAD
the only way to have it behave normally is to have all windows minimized, then the background for MyForm is AutoCAD