Puedes utilizar una función de la API. El ejemplo está sacado de www.allapi.net
Private Declare Function BlockInput Lib "user32" (ByVal fBlock As Long) As Long
Private Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)
Private Sub Form_Activate()
'KPD-Team 2000
'URL: http://www.allapi.net/
'E-Mail:
[email protected]
DoEvents
'block the mouse and keyboard input
BlockInput True
'wait 10 seconds before unblocking it
Sleep 10000
'unblock the mouse and keyboard input
BlockInput False
End Sub