I just found this thread which offers some solutions to the issue.  Here's the one I used: I went to the Task Manager, clicked on the Detail tab, went down the first row, found MiniSearchHost, right clicked on it, hit End Task and the translucent box went away. It might reappear but at least this takes it away! Must be a Windows Explorer 11 bug.
Hii. Recently I have been facing this issue of a small transparent rectangle appearing near the taskbar on my Inspiron 5402. The mouse pointer becomes the loading blue icon and I cant click anything in that rectangle. Restarting seems to fix it for now. Can you please help me out? [IMAGE]  
Transparent small rectangle on screen