I was trying to copy mp4 file. It showed some problem, but the file appeared as copied. When I try to access it, it can not be played and computer is starting to work veeeery slowly. I need to restart computer to get its normal speed back. When I try to delete the file - nothing at all happens. The file just stays where it is. It can not be cut nor deleted. I tried CCleaner - no change. I tried defragment - nothing again! Of course, untivirus checked and nothing reported. Computer works normally until I try to use that file. I can continue like this without accessing this file, but, first I am afraid it will spread, and I don't want to keep something is not behaiving normally on my computer. Suggestions????