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I suspect it could be click bombing... and I am wondering whether I should remove this site from the Authorized Sites list, or should I just let it be and Google will handle it?
A lot of us experienced a high degree of click bombing last month. So many, in fact, that it felt that there was safety in numbers. During the attack, I considered removing my site from the authorized list but decided not to do so. One reason was that I talked to support and she noted that it was a particularly bad month for fraudulent activity. So Google was aware of it. And people here on WebmasterWorld were able to track down the offending IP (Amazon) and block it (thanks in particular to Netmeg, Wa Desert Rat and others).
If, though, it seems as though you specifically are being targeted and others here are not, you might want to remove your site from the list until you can find the IP(s) to block. Talk to support, too, if you can.