dllhst3g.exe is a legitimate system process, which is related to Windows OS. It is an essential system's component, which is also known as Microsoft COM Surrogate. Please, do NOT terminate this file if you don't want to have issues related to your OS.
dllhst3g.exe can also be associated to malicious activity because any malware can be named anything for trying to hide its presence on the system. That's why there are lots of antiviruses that identify this file as Trojan.Gen.2, Downloader-BOW or Artemis!1DD8412EDB9B. During this scenario, this process can be used for data theft, installation of malware or such annoying activities as pop-up ads during people's browsing.
In order to make sure that your dllhst3g.exe is to related to malware, you should check it with a help of RegCure Pro.