Lately I have been manually updating MSE defs by downloading them here:
Since Nov. 12th, when I do this, it puts an icon on my desktop, but when I click on that icon, nothing happens. I can download them by opening MSE, going to the UPDATE tab and clicking on the UPDATE DEFINITIONS button.
Today when I opened the Action Center, there was an indication of a problem, although now I can't remember what it said. I click on "search for a solution", but it found none. I don't know if that message was related to the MSE issue.
My OS is Windows 7 - 64 bit.