Google's malware warning when placing ads on website

Hello all,

I guess Google is becoming more and more aggressive about other ad networks, as no matter which, whenever i place ad codes of any ad network (other then Google Adsense), google starts displaying the following message in webmasters control panel:

"Google has detected harmful content on some of your site’s pages. We recommend that you remove it as soon as possible. Until then, browsers such as Google Chrome will display a warning when users visit or download certain files from your site."

I've tried many different ad networks, and this issue happens with all.

What do you guys say on this, and any way to solve this issue?

I think google is doing great work so website owners need to remove low quality content and also remove third party adds, because now googlebot is more sharp and intelligent and can read the javascript and css files.