Windows ist offering Malicious Software Removal Tool KB890830 as normal update. But when having turned AVAST on (latest version – done yesterday) KB890830 may be installed, but is again told to be ready for download and installation, so it obviously did not install correctly.
If you want to break through that loop, you have to turn AVAST off; then it won’t come again and is installed as it should …
‘KB890830’ isn’t needed for you have ‘avast! AV’ installed. It doesn’t make any difference, if you have it installed or not. Instead of updating, you can hide this ‘KB890830’ update.
BTW: You should never turn off your AV, for your machine is unsecure then!!!
:
HDW
I don’t agree with you. KB890830 can find and remove some viruses, that can’t be found by Avast.
Last month I wrote about this problem in technical support, but they think, that making advertisments in http://market.yandex.ru is more important feature.
Another “fix” of problem - adding *\mrt.exe and *\mrtstub.exe in Avast file scanner exceptions.
I’ve never not installed a Malicious Software Removal Tool update.
I’ve also never had a problem downloading and installing these updates with Avast running.
Granted, these updates take a long time but do download and install.
I think that problem can be only on Windows XP (author of this thread also has it).
Why I still use Windows XP ? It’s a phylosophy question…
In Russia we have a proverb “Two heads are better than one”.
Other words, I have a primary antivirus Avast and periodically (once a week) run DrWeb CureIt scanner.
And every month Microsoft releases MRT scanner, that I use too.
Because there are no one solution to kill all 100% viruses.
This has been happening in my XP for about 4 or 5 MU. MRT downloads and ready to install, but although it says it installed, it is offered again and again. What I do is to installed it in safe mode.
To not be able to shut Avast down leaves me one alternative uninstall it. When I’m putting on Windows maintenance I have no idea in advance what Avast will interfer with. Malware bytes lets the user shut it down for different lengths of time or an event such as a restart. In my opinion they are doing it right and Avast is doing it wrong.
As you can see ( signature ) I never ever had any problems whatsoever with MRT. I still receive from MS security updates for office 2007 including MRT updates on a monthly basis.
It’s not the first time avast! prevented something from installing for no real reason.
https://rejzor.wordpress.com/2015/06/28/net-framework-3-5-error-0x80071a90-during-installaton/
Yeah, took me ages to figure out it was avast! that was causing this. Also one of the highest rated blog posts of all times on my page. I wonder if they’ve addressed it and potentially fixed what was causing it in the first place because it’s not normal at all that it blocks things like this.
I have also seen this problem. The affected Windows XP SP3 system uses Avast Free 10.4.2233 and has had the POSReady addition to its registry. Since the owner is very non-tech, it is a nuisance as she is unable to reliably manage the switching off then on again of Avast. The problem is that Windows update keeps offering KB890830 if the latest version cannot be installed.
When she flutters her eyelashes at me, I cannot resist and toddle round to her place to do the honours for her.
Point 1: I’m still using 'XP Sp 3 + ‘XP Update Extender’, the last one causes the ‘POSREADY’
additions! That’s ok.
But if she has an English XP-System, she doesn’t need ‘XP Update Extender’ for there is a
SP 4! So better update to that one!, only if ‘English’ OS!
Another question is: why did nobody update to the current version (11.1.2253) with the
user-defined possibility?
Point 2: ‘POSREADY’ has nothing to do with the registry, for it only supports ‘not enough tested’
updates! So it’s on someones own risk using ‘XP Update Extender’!
Point 3: KB890830 isn’t so neccessary, if you have a good AV software like avast!
Neither MS nor ‘XP Update Extender’ suppressed the apparent other one!
Mostly they come together, not caused by MS!!! For there’s no support at all for XP!
Point 4: :-X That’s only your turn.
Edit: Point 2 I’ve to correct, for ‘XP Update Extender’ misleads your OS to be another one
and so the updates are possible!
HDW
Does this ‘SP4’ mitigate recently discovered vulnerabilities such as the POSREADY updates do?
Avast 2016 11.1.2253 causes difficulties with Mozilla Thunderbird (running under Windows XP) which works OK with Avast 2015 10.4.2233 after the exclusion for nsemail.html has been dealt with.
I’ve asked avast! team about the .NET Framework problem several times and NEVER got an answer. And to my knowledge, the issue hasn’t been fixed. It only seems to be expanding further. Now regular updates are failing to install and that’s just BAD. People will stop using it if this nonsense continues.
Which I can’t confirm (see my sig, main machine and the other one are running very smooth).
See also → https://forum.avast.com/index.php?topic=162769.msg1298182#msg1298182
HDW
I also does not agree with this 
Consider the following (similar, but not identical to the author’s thread) scenario (where avast had to be completely uninstalled in order to provide basic maintenance to the computer?!)
A computer (Win7 32bit with up-to-date Avast running Ok, no viruses) was slow.
Hard Disk Sentinel reported vast amount of bat clusters on the hard drive.
The solution: run a ChkDsk utility on that drive.
However, when ever I attempted to schedule ChkDsk after the system restarted - ChkDsk failed to run with the exit message: this disk is locked due to unknown utility?!?
Mbam was then run on that system and Mbam found NOTHING.
After 3 whole days I figured it out:
(Accepted solution)
Why Avast on that computer was locking the drive and preventing the ChkDsk to run - newer actually figured out.
Supposed answer: Avast files itself were maybe damaged due to the bad clusters on that drive.
In that (possible?) case - Avast overlapped with ChkDsk or something, preventing tha ChkDsk to run.
I wonder if the Avast Self Defense Module might be the culprit ???
http://screencast-o-matic.com/screenshots/u/Lh/1457518337721-57364.png
Try unchecking the box as shown in the screenshot and see if that fixes the problem.