Killing Previous Instance of VB6 Application - vb6

Question

I've searched around for the proper way to kill a previous Instance of a VB6 application to no avail. If our main service dies, we need to terminate the previous instance of the running application and then, when the service comes back up only the new instance should be loaded. I am trying to exit this code in the following function:
Private Sub g_cServerInterface_FatalError(Error As enSvrReturns, ErrorString As String)
Dim sMsg As String
Dim result As VbMsgBoxResult
m_bFatalError = True
UnFreeze
If m_cLanguageText Is Nothing Then
GoTo TheEnd 'Form not yet loaded - not yet logged on
End If
' m_NumFatalErrors = m_NumFatalErrors + 1
' If m_NumFatalErrors > 5 Then
' Functions.DevInfo "Unable to restart Manitou.", g_cLangText_General
' End
' End If
If Error <> SVRERR_NOT_CONNECTED Or RunningInDebugger() Then
sMsg = g_cLangText_General.GetText("A system error has occurred")
If ErrorString <> "" Then
sMsg = sMsg & ":" & vbCrLf & vbCrLf & ErrorString & vbCrLf & vbCrLf
Else
sMsg = sMsg & ". "
End If
sMsg = sMsg & g_cLangText_General.GetText("Press OK to attempt to restart or Cancel to quit.")
result = DevAskOkCancel(sMsg, Nothing)
Else
' Since we've been disconnected, attempt immediately to reconnect
result = vbOK
End If
If (result = vbOK) Then
On Local Error Resume Next
If InStr(g_CommandLine, "-U") = 0 Then
g_CommandLine = g_CommandLine & " -U" & g_cUser.id
End If
If InStr(g_CommandLine, "-P") = 0 Then
g_CommandLine = g_CommandLine & " -P" & g_cUser.Password
End If
Shell App.Path & "\" & App.EXEName & " " & g_CommandLine & " -X", vbNormalFocus
DoEvents
End If
TheEnd:
If (Not RunningInDebugger()) Then
' Running as compiled executable
' Specifies the exit code for the process, and for all threads that
' are terminated as a result of this call. Use the GetExitCodeProcess
' function to retrieve the process's exit value. Use the GetExitCodeThread
' function to retrieve a thread's exit value.
CoUninitialize
ExitProcess 0
Else
' Running from the IDE
End
End If
End Sub
Note that I added the CoUninitialize and ExitProcess 0 API calls to this. How can I correctly terminate the previously loaded instance when the service comes back up? thanks Larry

Answer 1

Private Declare Function FindWindow Lib "user32" _
Alias "FindWindowA" (ByVal lpClassName As String, _
ByVal lpWindowName As String) As Long
Private Declare Function PostMessage Lib "user32" _
Alias "PostMessageA" (ByVal hwnd As Long, _
ByVal wMsg As Long, _
ByVal wParam As Long, _
lParam As Any) As Long
Private Const WM_CLOSE = &H10
Private Sub Form_Load()
Dim strCap As String
Dim lngHwnd As Long
Dim lngRet As Long
strCap = Me.Caption
Me.Caption = "*" & strCap
lngHwnd = FindWindow(ByVal vbNullString, ByVal strCap)
If lngHwnd <> 0 Then
PostMessage lngHwnd, WM_CLOSE, 0&, 0&
End If
Me.Caption = strCap
End Sub