New computer, running Vista. Keep getting this pop-up and cannot tell where it comes from.....AVG?, Windows Defender?, Spybot? ...don't know.

It comes up and says...."Application Execution" C:\Windows\system32\mswsock.dll

Seems that it's trying to tell me that there is some Application that is Executing through C:\windows\system32\mswsock.dll, but I have no idea what the Application is, or why it keeps coming up to tell me that.
I also still have no idea just what mswsock.dll is, even though I've tried researching it. Makes no sense to me.

Anyone able to shed some light please? What should I do, or look for?