Ntinvisible.dll is a Spyware.SpyAgent.B. Ntinvisible.dll is a commercial keylogger/system-monitoring program. Related files: %System%\ntinvisible.dll %Windir%\libimg.dll %Windir%\sbrowse.exe %Windir%\snmpapi.dll %Windir%\yahoodll.dll %ProgramFiles%\Spytech Software\Spytech SpyAgent\sagent.exe %ProgramFiles%\Spytech Software\Spytech SpyAgent\deploy.exe %ProgramFiles%\Spytech Software\Spytech SpyAgent\nostealth.exe %ProgramFiles%\Spytech Software\Spytech SpyAgent\sysdiag.exe Adds the value: "System32"="%ProgramFiles%\Spytech Software\Spytech SpyAgent\sysdiag.exe" to the Windows startup registry keys. More info: http://securityresponse.symantec.com/avc... Removal: Remove ntinvisible.dll from Windows startup using antivirus (also check How To Remove section)Startup Optimizer.