Windows 8.1 update : help needed.

[#1]

I don't think it was sneaky, there's nothing much in it for Microsoft if you use Defender.  I suspect it was inadequate testing on Microsoft's part; though to be fair testing something like that for a wide range of environments (including multiple AVs) is extraordinarily difficult.
Come the think of it, there is something in it for Microsoft if everybody uses Defender .... reduced testing time and cost, and reduced service costs sorting out where such issues do get through.  Sorting this out will have cost Avast! a lot in resources and in lost trust, but it will have cost Microsoft quite a bit too.

[#2]

A further thought on on this. I find that if left to itself Windows Defender uses automatic updates only once a day, but if the manual updating facility in the defender is used there appears to be several updates available - presumably all coordinated in the daily automatic update.
I've not been able to spot any means of arranging a more frequent auto update and I don't much like this.
Maybe it's back to avast now as it seems from the forum that it is now sorted.
Any thoughts from folk with expertise ?

[#3]

Finally decided to install KB3000850 yesterday.
Seems to be running ok with free version of Avast 

[#4]

Yep - me too 

[#5]

..........and me (AVG Free)

[#6]

Since win8 launch windows updates have been more risky.  I think this is due to the new rapid release in place now.

[#7]

I've not had any problems with updates.