I'm sure there's a much simpler way to do this, but I can't think of it off the top of my head, although this will do the job..

In a Module..
Code:
Public Declare Function EnumWindows Lib "user32" (ByVal lpEnumFunc As Long, ByVal lParam As Long) As Long
Private Declare Function ShowWindow Lib "user32" (ByVal hwnd As Long, ByVal nCmdShow As Long) As Long
Private Declare Function IsWindowVisible Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long) As Long

Private Const WS_MINIMIZEBOX = &H20000
Private Const SW_MINIMIZE = 6
Private Const GWL_STYLE = (-16)

Public Function EnumProc(ByVal hwnd As Long, ByVal lParam As Long) As Long
    'Make sure the Window is Visible and Minimizable..
    If IsWindowVisible(hwnd) Then
        If (GetWindowLong(hwnd, GWL_STYLE) And WS_MINIMIZEBOX) = WS_MINIMIZEBOX Then
            'Minimize it
            Call ShowWindow(hwnd, SW_MINIMIZE)
        End If
    End If
    EnumProc = hwnd
End Function
In a Form..
Code:
Private Sub Command1_Click()
    Call EnumWindows(AddressOf EnumProc, 0)
End Sub
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Aaron Young
Analyst Programmer
[email protected]
[email protected]