Option Explicit
 
Private Declare Function ShellExecute Lib "shell32.dll" Alias "ShellExecuteA" (ByVal hwnd As Long, ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, ByVal lpDirectory As String, ByVal nShowCmd As Long) As Long
 
Private Sub Form_Load()
    Call ShellExecute(Me.hwnd, "Open", "C:\prueba.txt", vbNull, vbNull, 1)
End Sub