C #. Net client CS program can only be started once

Using system;
Using system. Collections. Generic;
Using system. LINQ;
Using system. Windows. forms;
Using Microsoft. VisualBasic. applicationservices;

Namespace myquery. myie
{
Static class Program
{
/// <Summary>
/// Main entry point of the application.
/// </Summary>
[Stathread]
Static void main ()
{
Application. enablevisualstyles ();
Application. setcompatibletextrenderingdefault (false );
Singleinstancemanager manager = new singleinstancemanager (); // Single Instance Manager
Manager. Run (New String [] {});
// Application. Run (New frmbrower ());
}
}
Public class singleinstancemanager: windowsformsapplicationbase
{
Frmbrower app;
Public singleinstancemanager ()
{
This. issingleinstance = true;
}

Protected override bool onstartup (Microsoft. VisualBasic. applicationservices. startupeventargs E)
{
APP = new frmbrower ();
Application. Run (APP );
Return false;
}

Protected override void onstartupnextinstance (startupnextinstanceeventargs eventargs)
{
Base. onstartupnextinstance (eventargs );
App. Activate ();
MessageBox. Show ("the client program is already running and cannot be run repeatedly", "warning", messageboxbuttons. OK, messageboxicon. Stop); // prompt a dialog box
}

}
}
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