netmeg - 11:23 pm on Feb 21, 2012 (gmt 0)
Strikes me it fits the profile of a windows virus botnet type thing - for me at least, it's all IE (different versions) from all different IP numbers. I dunno what they're looking for - WordPress vulnerabilities? That's what my host thinks, anyway.
I disabled my ads on the site for the time being, as I would rather not be kicked out of AdSense on account of it.