After five years an adsense publisher got deactivated for unknown reasons without any notification.
Google says, some mail had been sent, but despite the receiving account is on Google aps gmail, nothing has been received.
No longer access to the account, support does not respond and the domains that were hit were all clean and proper content sites with loads of rich media and valuable information with many first page listings since many years.
This might be a fair warning for all adsense publishers.
Google may freeze your adsense account without any notice at any time.
In Japan this also seems to be happening fairly often.