Public Declare Function FindWindow Lib "user32" _
  Alias "FindWindowA" ( _
  ByVal lpClassName As String, _
  ByVal lpWindowName As String) As Long

Dim sTitel As String
Dim lhWnd As Long
 
sTitel = "exakter Fenstertitel"
lhWnd = FindWindow(vbNullString, sTitel)
If lhWnd <> 0 Then
  MsgBox "Anwendung läuft..."
End If