I have been observing that Process.HasExited sometimes returns true even though the process is still running.

My code below starts a process with name "testprogram.exe" and then waits for it to exit. The problem is that sometimes I get thrown the exception; it seems that even though HasExited returns TRUE the process itself is still alive in the system - how can this be??

My program writes to a logfile just before it terminates and thus I need to be absolutely sure that this logfile exists (aka the process has terminated/finished) before reading it. Continuously checking for it's existence is not an option.

        // Create new process object
        process = new Process();

        // Setup event handlers
        process.EnableRaisingEvents = true;
        process.OutputDataReceived += OutputDataReceivedEvent;
        process.ErrorDataReceived += ErrorDataReceivedEvent;
        process.Exited += ProgramExitedEvent;

        // Setup start info
        ProcessStartInfo psi = new ProcessStartInfo
                                   {
                                       FileName = ExePath,
                                       UseShellExecute = false, // Must be false to redirect IO
                                       RedirectStandardOutput = true,
                                       RedirectStandardError = true,
                                       Arguments = arguments
                                   };

        process.StartInfo = psi;

        // Start the program
        process.Start();


        while (!process.HasExited)
            Thread.Sleep( 500 );

        Process[] p = Process.GetProcessesByName( "testprogram" );

        if ( p.Length != 0 )
            throw new Exception("Oh oh");