Slide.Export() closes PowerPoint menus when it is called

Question

I am developing a VSTO add-in for PowerPoint, where every 5 seconds a slide that is currently selected needs to be saved as image. The code looks like this:

public partial class ThisAddIn
    {
        public Form form = new Form
        {
            Opacity = 0.01,
            Visible = false,
        };
    delegate void InvokeEventHandler();

    private void ThisAddIn_Startup(object sender, System.EventArgs e)
    {
        form.Show();

        var del = new InvokeEventHandler(() => Timer_Tick());
        form.Invoke(del);
        var timer = new System.Windows.Forms.Timer();
        timer.Interval = 5000;
        timer.Tick+= (s, ea) => form.Invoke(del);
        timer.Start();
    }

    private void Timer_Tick()
    {
        try
        {
            var slide = (Slide)Application.ActiveWindow.View.Slide;
            slide.Export(Path.Combine(Path.GetTempPath(), "test"), "png");
        }
        catch
        {
            return;
        }
    }
}

This code works, but unfortunately every time the timer ticks (specifically, every time Slide.Export() is called), it looks like PowerPoint window freezes for a split second, and all expanded menus get closed. For example, if you open the right-click menu on any slide and wait for 5 seconds, it will close once the timer ticks.
Is there any way to fix this?

Thanks