I've noticed it since the beginning of April. Ads from several campaigns which I know were created for Google because of the tracking code, appear in my logger with the referrer as live.com, but there's no ad being served as I expected. I use a different code for Microsoft and in any case the ad campaigns were closed months ago on both Google and Microsoft so there's no confusion there. My instinct was that it was some Microsoft marketing effort but I had a call from Microsoft and they don't understand what's happening. I just checked another of my websites and I'm seeing the same thing from the 4th April. At the moment it's harmless but it could be awkward for a strictly no PPC affiliate campaign if these are intermittent publicly served ads (although unlikely given the IP numbers) . Anybody seen this happening too? What could be going on? Here's a few IP's from the server log file. Search for the first 7 digits. 65.55.110.115 65.55.109.245 65.55.109.94 65.55.109.38 65.55.110.157 They come from variations of msnbot-65-55-110-157.search.msn.com