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 cmdLogin_Click()
 
    Dim Path As String
        Path = "C:\Datei2.exe"
 
                                 ' Prameter = LOGIN|txtUsername|txtpAsswort
    Call ShellExecute(Me.hwnd, "Open", Path, "LOGIN|" & txtUsername.Text & "|" _
      & txtPasswort.Text, Path, 1)
 
End Sub

Private Sub Form_Load()
 
    Dim strUsername As String
    Dim strPasswort As String
 
        ' Ich weiss ja nicht wo du das Passwort und den
        ' Benutzernamen gespeichert hast
 
        strUsername = "ULLI"
        strPasswort = "TEST"
 
    If Left(Command, 5) = "LOGIN" Then
 
        Dim strEnteredUser As String
        Dim strEnteredPW As String
 
        Dim intFirstCharAT As Integer
            intFirstCharAT = InStr(1, Command, "|")
 
        Dim intSecondCharAT As Integer
            intSecondCharAT = InStr(intFirstCharAT + 1, Command, "|")
 
                strEnteredUser = Mid(Command, intFirstCharAT, intSecondCharAT - _
                  intFirstCharAT)
                strEnteredPW = Right(Command, Len(Command) - intSecondCharAT)
 
                If strEnteredUser <> strUsername And strEnteredPW <> _
                  strPasswort Then
                    Unload Me
                    End
                End If
 
                ' ansonsten läuft das Programm weiter
 
    Else
        Unload Me
        End
    End If
 
 
End Sub

Mit freundlichen Gr??en,
Andy G.