The thing is that the ContextMenu is build by Windows. MC is just calling Windows to show a context menu for item X.. Everything behind the scene is handled by windows.
When the popup menu is bulit the first time it will loads all of the registered shell extension into MC and this can takes some time.
Normally only the first time it shows it, it is slow. So some shell extension is taking its time to decide what menu items it what to add to the popup menu (if any)
The problem is that it is not very easy to figure out what shell extension is slowing it down.
Have you installed any new shell extension resonantly ?
Also most shell extension are also only tested for WindowsExplorer and some of them assume that the calling windows is Windows Explorer, And when it is not they can behavior strange.
Also some shell extension is not working well together with other shell extension. I seen all kind of crazy thing with badly written shell extension.
But that why someone created a tool to easily list and enable/disable them : ShellExView (
http://www.nirsoft.net/utils/shexview.html )
Shell Extension are know to be able to cause many strange issues.
Weird issues by context menu handlersDisappearing Menu is something else. Something must steal the focus away from MC. It is strange that the language thing goes away and comes back.
Also the dropdown box on the taskbar look suspicious. ComboBoxes 'can' steal focus if they are repositions. and since the language button is removed this is moved.
Anyway.. something is interfering with the showing of the menu.
Is it only the context menu that gets canceled ? or is it all popup menus ? likeif you right click on commandline field or right click on the filter icon.