A few years ago, I followed a tip I read about a list of ad sites that
you could exclude when using a browser. I'm thinking it was a system
file as it works in multiple browsers. It provided a list of
sites I added to a file I opened in a text editor.  As of late it
seems to create a problem when I have been looking over the cnet
family of sites.

For the life of me I can't remember where the file is, or find the
info that I referenced when I did it.

So what I need is the file name that the system checks so I can modify the file.

The file you are looking for is the "hosts" file, located in one of
the following folders:
Windows XP = C:\WINDOWS\SYSTEM32\DRIVERS\ETC
Windows 2K\NT = C:\WINNT\SYSTEM32\DRIVERS\ETC
Windows 98\ME = C:\WINDOWS