Arrows, tab and other "position" keys suddenly don't work

Hi,
I’ve problem with my keyboard probably. I’ve upgraded to 11.3 and everything OK, after a short time some problems appeared. When I want to jump through forms per TAB button, it doesn’t work. When I want to edit text in such tinymce-like editors, my arrow keys don’t work, I can only insert and delete chars, when I need to change position, I must use mouse cursor (I’ve discovered that keyboard works properly in raw html mode). In these situation also ctrl+V, ctrl+C and others don’t work.
When in normal text editor, it’S ok.
It was working before and I don’t know what’s changed.
Thank you for tips!
lac