acs.exe is a worm W32.Kelvir.W. acs.exe spreads by MSN Messenger and via open network shares . acs.exe tries to terminate antiviral programs installed on a user computer. acs.exe monitors user Internet activity and private information. It sends stolen data to a hacker site. Related files: %ProgramFiles%\ACS-Style\rxBot.exe %ProgramFiles%\ACS-Style\acs.exe %system%\winsystem32xp.exe More info: http://securityresponse.symantec.com/avc... Removal: Kill acs.exe process and remove acs.exe from Windows startup using antivirus (also check How To Remove section)Startup Optimizer.