Try the following combo button events.
Code:
Private Sub Form_Load()
Me.cboSerial = Me.cboSerial.ItemData(0)
End Sub
Code:
Private Sub cmbSysID_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)
If Button = acRightButton Then
Me.ShortcutMenu = False
Me.cmbSysID.Dropdown
End If
End Sub
Edit: if you don't want all of the rest of the shortcut menu functions to be disabled on that form after the mouse event runs, turn the shortcut menu back on as in
Code:
If Button = acRightButton Then
With Me
.ShortcutMenu = False
.cmbSysID.Dropdown
.ShortcutMenu = True
End With
End If