Same issue here on Win 8.1 x64 after KB3000850 while running the latest avast. Going to uninstall avast now in safe-mode…
UPDATE: Removing Avast fixed all the issues.
Confirmed KB3000850 breaks Avast! 2015.10.0.2208 and Windows 8.1 x64 when used together. I had to do a system restore to get my system functional again. Please fix.
same symptoms I experienced on two machines… I believe this is only the 8.1.1 x64 version issue
Not for everyone.
My system is the same as before the update in fact I was surprised when I saw people were having issues.
Part of the update was Defence-in-depth security and Schannel hardening
Maybe that is why some are having issues.
Completely broke my perfectly working 8.1 with Avast Pro 2015. As others have had, couldn’t shutdown/restart, IE crashed on opening, control panel unresponsive.
Removed Avast using the cleaning tool in Windows (not safe mode), rebooted and everything worked great. Until Avast fix this issue, I have removed the new update and reinstalled Avast and everything is working fine again.
What a mess.
Hope this gets fixed ASAP as this is a serious issue.
Last update i was having a language problem with avast?
Now with this update of win 8.1 i have more then only the language problem.
IE wont open, system settings wont open and a few others.
Then after a reboot i couldt not go online and what more.
Need to use my computer to see what is wrong here, and see lots of post here on this forum.
Been busy whole afternoon to uninstall Avast ( and also use the tool in safemode ).
Now avast is gone, and i guess i will not re install it again.
After so many years, i think i say bye bye to avast ( was having more problems since i have win 8.X and avast )
And my laptop is working good and fast.
And without any problems ( quick reboot, start and shutoff. ANd files and programs are opening also alot quicker then before with avast)
I can also confirm it.
W7 x64 with all latest updates. It did not occur after initial restart (to apply updates) but after second or so…
Windows 8.1.1, all the updates till now.
Same here, same problems, same way. Uninstalling Avast fixed all the issues brought by KB3000850. Issues (at least at my end) were, problems with:
Control Panel,
God Mode (some other win functions too),
No shutdown or restart,
Hybrid Shutdown works to some extent (Shuts Windows but not computer)
After Avast uninstall ( Avast own tool in safe mode), Windows Defender is not returned to previous state and WD service is completely missing. Dism /online repairs did not bring it back.
To top it all, no valid response from Avast team, explanation how windows update broke Avast is completely unsatisfactory, ignoring problem, even more so.
Not caring for their product or customers, put’s any product on my black list despite many years of use, recommendations and installations on many computers, mine or customer’s ( both free and commercial versions). I didn’t notice any other major AVs to have those problems.
In conclusion, Avast has slipped badly lately. Not working on Win 10 TP (while many other AVs do), I can get over but braking a major OS is unforgivable. Ad to that affair with spying and it’s enough for me to wish it a swift demise.
My recommendation on many IT forums I’m active on, will be BYPASS AVAST !!! GET RID OF IT if you use it. !!!
Have you rebooted your PC a second time after the install ?
Seems some are affected right at install reboot…some after an additional reboot.
Avast Team…where are you ?
NEEDED: Bootable Util (CD/USB) for Uninstall/Clear
P.S. I mentioned this in many threads over the past…Avast needs a util that will cleanly uninstall a locked-out/bricked machine. Yes, I know there is AvastClear (which is AWESOME) but that requires you to be able to get into Safe or Windows mode. What happens if machines cannot get there ? I fear as Avast gets more intrusive into O/S this can/will happen.
My suggestion, as I’ve asked before, is a util (ISO) that people can burn to CD (or USB stick) that is “bootable” so a user can boot to this program and brute force delete/uninstall ALL Avast remnants. Avast does have Rescue CD but that is A/V removal type app. I cannot stress how important something like this simple util could be to Avast and its users. I hope Avast Team will consider/develop…it would not be hard…maybe a days work by Avast developer.
+1
I have been able to uninstall KB 3000850 as booting the machine up this morning avast was giving errors and not functioning correctly, I then proceeded to attempt to uninstall KB3000850 and for the first time in over 30 attempts i was able to do so. Which i am guessing was down to Avast not functioning correctly.
If you are still having issues with it i suggest you post in the thread i opened with MS in hope both Avast and MS can work something out to fix things asap.
http://answers.microsoft.com/en-us/windows/forum/windows8_1-windows_update/major-issues-with-kb3000850/5cb4cddd-52da-44af-9fd5-3ae1a72b0b1a. Because so far both avast and ms have been very quite with saying anything up until this point. 
I can confirm I experienced the same issue with KB 3000850 on Win 8.1 64-bit. Of course I was unable to uninstall that patch, so I had to boot in safe mode to uninstall Avast, and I had no problem anymore.
Another odd observation: I run my Win 8.1 partition both through VMware Fusion and dual-booting on my MacBook Pro, and the issues appeared only when it was running under VMware. I highly suspect there’s a race condition or timing that triggers the issues on slower computers.
Yet another odd observation: I kept trying to reinstall the VMware Additions to see if it makes any difference, and the installer would get stuck trying to install the VMware Thin Print drivers. After uninstalling Avast, I could install the Additions without problem.
No I installed the other two updates first… I left the big (bad ) one 'till later
Thank you.
I’ve installed them all and i don’t see any difference.
Same problem after installing KB3000850. Windows 8.1 x64, Avast Free 2015.
BTW, is there a ticket or bug report about this issue?
It would be useful to find out what the commonality is apart from Avast, especially as it has not affected all windows 8.1.1 with Avast
The same here with Avast Endpoint protection plus. IE wont start, PC wont shutdown or reboot, Visual Studio’s post-build was not working (probably cmd was screwed). I uninstalled Avast without switching to Safe Mode (killing all its processes first) and the issues were fixed after shutting off power manually. I switched to Windows Defender and I will probably not pay again for this software as the only thing it does is it bothers me with many FPs.
Maybe logitech SetPoint software? I have it and I saw it mentioned couple of times by other guys. But it’s just a wild guess, I can’t see a way how could SetPoint affect OS in such a way…
I’m not 100% sure this is totally related to NG and installing this update. I have updated 4 systems with NG enabled and haven’t had a single issue.
Just want to add this to help the devs narrow down the cause of these problems.
