own file of the operating system Microsoft Windows, reason why a threat to the operating system does not have to be considered as. It considers that the valid process rundll32.exe of Windows is located in C: WindowsSystem32rundll32.exe, but some times the virus, spyware or malware generally use the same file name (to confuse the user) and they are executed from a directory different from previously mentioned. If suspicions that a called file rundll32.exe is being ejecuntando from a location different from the original one from Windows, then you can try to do I scan with a program commercial anti-virus free or a anti-virus.