Don't mean to be a pain here, but 7 is not the "latest." Try to answer questions a little more precisely if you want the free help.
I was asking for reasons of clarity really...for a moment I wondered if somehow the log was reporting a different OS version than what the rest of Windows was reporting.
Try deleting the downloads cache and going at it again. That might resolve the issue, if there was download corruption (though, in the case of a signature not checking out, windows should discard the file immediately - it's a long shot, but it might work.)
If that doesn't work and it's the same error, we can look into other possibilities which range from the content not being signed correctly, or your system not having the correct root certificate.