If you haven't already, try resetting Chrome's install.
- Settings > "Reset settings" (Under the "show advanced settings" link on the bottom of that page.)
It sounds like you've already taken care of changing the larger parts of the settings, but there's most likely something else that's either hijacking the browser or running on the system, waiting to hijack webpage traffic to insert the ads into. Resetting Chrome's settings should take care of the issue if it's just the browser that's being affected.
If that does not fix the issue, I would conciser doing the following:
- in Windows, go to Control Panel -> Internet Options and look under the Connections tab.
- Click on LAN Settings and make sure that "Use a Proxy Server for your LAN" is unchecked.
From there, you should do a virus/malware scan on the PC. Lately I've had a ton of success with ESET Online Scanner in finding and getting of programs that causes these types of hijacks on the system.
There are many more possible issues and fixes out there, but this is a very general first-step I would take to a machine before going hardcore with it. As always, don't forget in using Google from a working machine and do a search for the ad-network, hope that helps!