Sistem32.dll is a worm W32.Clunk.A. Sistem32.dll tries to terminate antiviral programs installed on a user computer. Sistem32.dll monitors user Internet activity and private information. It sends stolen data to a hacker site. Sistem32.dll spreads by e-mail and via open network shares. Related files: %Windir%\sistem32.dll %Windir%\WinUsr.exe C:\Documents and Settings\All Users\Start Menu\Programs\Desktop Manager.lnk Adds the value: "WinUsr" = "%Windir%\WinUsr.exe K1S2" to the Windows startup registry keys. More info: http://securityresponse.symantec.com/avc... Removal: Remove sistem32.dll from Windows startup using antivirus (also check How To Remove section)Startup Optimizer.