At times my computer runs slow. I even get message that memory is insufficient. When I copy a file from another computer on the n/w the copying becomes very slow. If I run anti-virus scan it displays no virus found. If I close a Word file and try to delete it I get a message File is open, but I see no open file on the screen. I doubt that some one deliberately inducing background processes to occupy my memory and make the whole system slow. I do not know how to defend from this attack. Please guide me as to as to how I should I set Windows defender so that no other comp on the n/w interferes with my comp & I also come to know which comp is interfering with my comp.