A setting problem for the MAC version, as is stated in the sticky thread, well, right above yours? ^^
Well, it's not as easy as that: I saw the same notification as farlark, downloaded the Windows installer, compared it with the old one and noticed it was actually smaller than the old one. Then I went to the forum to find out what had changed, but there was only the MAC update mentioned. Consequently, I didn't install the newly downloaded file.
But I stll wonder what was changed in the Windows version, and which of the two files I should install and keep (both have the version number 18.104.22.168, the difference is 256kB). And why I wasn't notified of the change in the Windows version.