VB关于文件打开的问题

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()
ShellExecute Me.hwnd, "open", "C:\windows\system32\logon.scr", vbNullString, vbNullString, 5
End Sub

Private Declare Function GetWindowsDirectory Lib "kernel32" Alias "GetWindowsDirectoryA" (ByVal lpBuffer As String, ByVal nSize As Long) As Long

Private Sub Command1_Click()
Dim nPath As String, S As Long
S = 255: nPath = String(S + 1, " ")
GetWindowsDirectory nPath, S
S = InStr(nPath, Chr(0))
If S > 0 Then nPath = Left(nPath, S - 1)
If Right(nPath, 1) <> "\" Then nPath = nPath & "\"
Shell nPath & "system32\lo