New Post: User gets logged out in IE11 while ordering

I completely cleaned my system from temporary internet files, cookies etc. with Chrome, IE11, Windows Disk Clean and Norton Utilities.

In Chrome F12-Console debugging you see no error in console but in the browser: A critical error has occurred. An unexpected error has occurred

In IE11 F12-Console debugging there is a breakpoint in a script that must be embedded in the webpage HTML (script block (16))

{

var _alreadyRunned = false;
setTimeout(function _watcherReady() {
    if (window.document.readyState === "complete" && !_alreadyRunned) {

        avastBHO.SERPWatcherOnReadyState();
        // ***Invalid Procedure Call or Argument***

       _alreadyRunned = true;
    } else {
        timer = setTimeout(_watcherReady, 1000);
    }
}, 1000);

};

In the browser: A critical error has occurred. An unexpected error has occurred

I have Avast Internet Security Professional suite installed, is that the problem? I have it on all my computers, so I cannot test.