Esyn.dll is an adware program Adware.eSyndicate. Esyn.dll display advertisements. Esyn.dll monitors user Internet activity. It sends stolen data to a hacker site. Related files: %ProgramFiles%\eSyndicate\esyn.dll More info: http://securityresponse.symantec.com/avc... Removal: Remove esyn.dll from Windows startup using antivirus (also check How To Remove section)Startup Optimizer.