Cefsharp browser app, Sendkeys error

I have a windows application in c#. There is a browser using CefSharp. I'm send username and password and login to instagram. so when lock my windows that app give me error message. I added my simple browser project, you can download and fix the problem. You can downoad my simple browser project: [login to view URL] Error details: See the end of this message for details on invoking just-in-time (JIT) debugging instead of this dialog box. ************** Exception Text ************** [login to view URL] (0x80004005): Access is denied at [login to view URL](Byte[] oldKeyboardState, Queue previousEvents) at [login to view URL](String keys, Control control, Boolean wait) at [login to view URL](String keys) at InstaBrowser.BrowserForm.tmrAltTab_Tick(Object sender, EventArgs e) in C:\Users\[login to view URL]\source\repos\InstaSharper-develop_new\ProxyBrowser\ProxyBrowser\ProxyBrowser\[login to view URL]:line 311 at [login to view URL](EventArgs e) at [login to view URL](Message& m) at [login to view URL](IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)