ArcGIS - Editor toolbar not opening

I have installed ArcGIS Desktop 10.5.1 on a new computer and have a problem that I have never experienced with any previous versions of ArcMap.

Pressing the button of the toolbar for the Editor I can’t access the toolbar. Neither does it open if I go to Customize – Toolbars and cross in the box for it there. All other Toolbars seem to open correctly.

I also can see that the program notices that I have pressed the button by the ArcMap-window ‘flickering’ and I see the Editor-toolbar that should open for less than a second at some occasions.

I have tried to see if it ends up hidden somewhere, but it does not seems like it.

Does anyone know what can be the problem and how to handle it?

I have tried to search for answers both at the ESRI help-page, here in previous asked questions and in other broad search engines, but this doesn’t seem to be a common problem.