ObjectDisposedException

Question

Hi,
I created a pop-up window that is opened through menu. When I click the menuitem, I use this code to make the form visible:
[code]
popupform.Show();
[/code]
After I close the popup form and then try to open it again it says
[quote]
System.ObjectDisposedException: Cannot access a disposed object.
Object name: 'Form'
[/quote]