Been in adsense for years now and normally there are 5-10 invalid clicks each month that are charged back. Highest amount was something like $25.
This month, there has been a charge back of over 200 clicks-worth. A quarter of my earnings.
We've altered the site quite alot in the past month (new layout, design and more social networking). But the revenue has been almost the same as previous months as the ads are not on all our pages anyway, just the news articles.
The number of clicks have not gone up, just the amount of invalid clicks. So I'm guessing it's not an external source causing the problems?
Why would a quarter of our traffic suddenly be "invalid"?