VS 2008 - Windows Dialog Forms Hidden But Not Closed

I am using a Windows Dialog form in my VB 2008 project. I bring up the dialog form no problem with the following
Dim resultNewInc As DialogResult
resultNewInc = frmDialog.ShowDialog()
If resultNewInc = DialogResult.OK Then
...some code here ...
End If

And in the Dialog Form, the OK button has code
Me.DialogResult = System.Windows.Forms.DialogResult.OK
Me.Close()

But there is one problem. If I call up the dialog form again, the form controls have the text values that were typed in during the previous instantiation and a class which is part of the form was not disposed. So it looks like the form is being "hidden" and not closed. I tried to use the code form.dispose but it didn't work.