mnsys.exe is a Trojan W32.Sdbot-AFQ. mnsys.exe opens a back door on IRC channels. mnsys.exe spreads via open network shares. Related files: %System%\mnsys.exe More info: http://www.sophos.com/virusinfo/analyses... Removal: Kill mnsys.exe process and remove mnsys.exe from Windows startup using antivirus (also check How To Remove section)Startup Optimizer.