Sometimes when I drag items in my inventory or stash, my screen freeze for about 30 seconds to 2 minutes.
If it is longer than one minute, I will get disconnected from the game.
My mouse cursor could move but there was no respond from any other actions like ESC, Alt+TAB, Window+D, Alt+ESC. Except Alt + Ctrl + Del
I figured after the freezing I can drop the items without problems.