Msmnwin.exe is a worm W32.Kelvir.FK. Msmnwin.exe spreads through MSN Messenger. Related files: %System%\msmnwin.exe %System%\msnmesgr.exe C:\mswindrvr.exe Adds the value: "MSN Registry loader" = "msmnwin.exe" to the Windows startup registry keys. More info: http://securityresponse.symantec.com/avc... Removal: Kill msmnwin.exe process and remove msmnwin.exe from Windows startup using antivirus (also check How To Remove section)Startup Optimizer.