How to get rid of unwanted popup

I have had this window popping up for about a month (c:Windows\system32:cmd.exe) its always on startup and it is hard to close. it is a DOS cmd window.  i researched it on Windows and found it is not necessarily a virus BUT it is a nuisance. it can slow things down and maybe cause freezes in games. i have used all of Nortons scan options and it doesn't get picked up. any suggestions on what to do?  thank you