So I see KB3035583 has moved back from optional to recommended.
All Googling shows this is for upgrade to W10.....which I'll never do on these PCs.
I see there is also an optional Skype KB.....which I will hide.
Anyway, I went ahead (today 4/3/2015) and installed on five W7 64bit machine with Avast 9 last release and one PC with latest Avast 10....all went fine.