Follow these steps:

1. Put two imageboxes on form1
2. name them icon1 and icon2
3. load the two icons to the imageboxes
4. add a timer and set the interval(1000?)
5. add this code

Public which As Boolean
Private Sub Timer1_Timer()
Select Case which
Case True
Form1.Icon = icon1.Picture
which = False
Case False
Form1.Icon = icon2.Picture
which = True
End Select
End Sub