Works fine for me under Win98:
Code:
Private Declare Function SendMessage _
Lib "user32" Alias "SendMessageA" _
(ByVal hwnd As Long, ByVal wMsg As Long, _
ByVal wParam As Long, ByVal lParam As Long) As Long
Private Declare Function GetDesktopWindow Lib "user32" () As Long
Const WM_SYSCOMMAND = &H112&
Const SC_SCREENSAVE = &HF140&
Public Sub ActivateScreenSaver()
Dim ret As Long 'junk return value
Dim desktop As Long 'desktop handle
desktop = GetDesktopWindow
ret = SendMessage(desktop, WM_SYSCOMMAND, SC_SCREENSAVE, 0&)
End Sub