I use the same ad networks as the majority of sites use ..... Google and Double Click. Well, I use OutsideHub, but they run everything through Double Click and feed a lot of Google ads. Both companies deliver ads based on user behavior, tracked and logged based on what you are searching for, sites you view, etc.
Most ads you see here should be about the same as those same ad networks deliver to you on other sites as well.
The only other ads delivered on this site are ads I control, which are not "smart" ads at all, but simple JPEG or GIF files linking to an advertisers site.
After some digging, it appears that the Microsoft Security Essentials issue is a malware thing on individual computers. It's fake. It's not really seeing a security issue, whether you get the alert while looking at this site or any other. It's a fake alert that calls for a person to download some software. That has nothing to do with this site and would infect a persons computer if they downloaded something.
Now, as I posted above, there was an issue once where one of the forum users here was getting a legitimate alert from their security software because of something it saw on one of our pages. It was another users old signature image link. The image no longer existed, but the link was still in the user signature. So the web address still showed up in the code of this site. The domain name in the address was suspect, so the security software threw an alert.
There was no threat, but all the security programs can do is watch for suspect files, domain names, etc. and then "suggest" that a webpage might be a security threat. Many times they are not.
I believe it is possible for a malware/virus type ad to slip through one of the networks and be delivered to this site, but I doubt it happens too often. Google has a couple smart programmers and a little money to throw at security of their ad network, as does Double Click.
All I can say is, if you get some sort of alert of a security threat from your security software while looking at this site, let me know what page you were looking at when it happened, and if possible, any ads you see on the page. I can then look into it.
Brian Latturner
MonsterMuleys.com