I confirm that Google bans AdSense accounts without any warnings. More, even without any explanations. I started to use AdSense for several very different virtual servers and they banned my account with stupid explanation that "they discover invalid clicks on my service". I tried to make them be more specific, but they just ignored me. Which service? I have many of them. The are just arrogant bastards. They are also stupid because everybody can attack other AdSense account in quite easy way. AdSense account can be also fooled in easy way. What a problem to generate random clicks using anonymous proxies and simple script?