I think google will not ban anyone for such things. Why? bz no one can stop others or spammers from clicking on ur ads. for example, if a person hate a site that use google ads and is earning good, so in order to ban that site, all he has to do is to start clicking on that site ads, will google ban that site?
I know that at least in vBulletin's case, there are a few mods for proxy->actual IP conversion that may help a bit.
similar thing happened to me yesterday... but in my case I think it is a reporting error on google's part. i have two url channels created for that site: www.site.com and site.com www.site.com reported 21 clicks while site.com reported 81 clicks the earning were the same for both channels. the difference between www and non www is that non www tracks clicks on all subdomains. so I check the subdomain.site.com channel and saw NO clicks..... now, that is the miracle as I do not have any ads that do not have channels I sent an email to google saying that I am very concerned and would like to know what happened. also, I reviewed the logs and did not find any suspicious activity and I mentioned that as well... I did not receive a reply yet, will see what google has to say. cheers.