Also FYI, we've been in touch with Google about the issue, who is (well) aware, and working on it. It's currently affecting thousands of web sites, so one hopes that the size will lead to a faster resolution.
the same thing just happened to me! a whole new window popped up "open software updater" and i went to close and it says the update was important but i closed it anyway because it was clearly a scam. glad to hear it's being worked on :)