I have been seeing reports of Google banning and disabling AdSense accounts due to using a Firefox plugin named Tamper Data. Tamper Data allows people to view and modify HTTP/HTTPS headers and post parameters, which can be helpful, but also used for evil.
The emails being sent to these publishers read:
During a recent review of your account, our specialists found that tamper data was used to modify the country listed in your account. Changing your address in this manner is a violation of our policy guidelines.
What appears is happening is that publishers are signing up using Tamper Data to fake their location. You can read why and how this is done at this blog and this one.
In summary, certain countries are not allowed to sign up for AdSense so people fake where they are from. I am not sure why people would use this technique when they are in an approved location, unless I am missing something?
You can read the dozens of threads about this at Google AdSense Help or a thread at WebmasterWorld.
