Wow, I really thought at first that it was fake, since Google discourages people to use third-party softwares, but hell the header told the truth and set us free. Good luck on this challenge Col, I know it's hard, knowing that you had the account for 2 years already, and you're earning a lot, I know.
Well that's the annoying thing. I'm not earning much on adsense at all at the moment. What little amounts I get from Adsense is surely a bonus. It would not be that big a deal if it were banned but it would sure wreck some of the projects I am working on now. I hope they will at least reply to my two emails to find out a little more info.
http://www.phpadsnew.com/two/ Thats one to use. http://www.adbutler.com/ Another has high Alexa traffic but no PR
Check your stats to see if you are getting visits from any paid-to click, paid-to-surf, paid-to-read, or similar sites. That's what they said the problem was... people being paid or given other incentives to visit your site. Hope you get it sorted out.