I have a Windows 7 (64) PC with Microsoft security essentials running and up to date. I have recently found that when I load certain websites which never previously contained adverts, now they do. I.e. I view the website (e.g. news.bbc.co.uk), everything looks normal, but then some ads appear inserted into the text. Clearly I have some sort of malware, but no software I have tried appears able to detect it. I have run adaware - all clear. Trend micro's housecall - all clear, Kaspersky's TDSSKiller - no threats found, malwarebytes - zilch. I have uninstalled all software that has been installed recently. The errors appear on both chrome and firefox, but not internet explorer.
I wonder if the corruption is working at some different level altogether that fundamentally cannot be detected by virus scanners.
I have a laptop connected wirelessly to the same network and no such ads appear on that.
EDIT: Just noticed that there are references to "aducky" in my registry.
EDIT: also now tried both Sophos and Norton. Both say nothing found.
EDIT: Here is an example screenshot viewing a website with chrome.
EDIT: and here is process explorer...