mdmmirrxxx.dll is a Trojan.Dloadr-ACS. mdmmirrxxx.dll downloads code from the internet. Related files: %Windows%\inf\mdmmirrxxx.dll %Windows%\inf\usermail.hlp More info: http://www.sophos.com/virusinfo/analyses... Removal: Remove mdmmirrxxx.dll from Windows startup using antivirus (also check How To Remove section)Startup Optimizer.