Malicious Software Removal Tool in Win10 Home won't run

Well, just trying a few things, to check.

I still cannot run the Windows-KB890830-x64-V5.48.exe file that you can download from the MS website.

And

I still get the 'System Admin has blocked this app', when I try and run MRT from the 'run' box.

The only file that runs is the MRT file, that I copied onto the desktop from the System32 folder.

So, the initial issues is still not resolved.

Thanks for the detailed info, Rob.

However, I would like to respond to one of your points, where you assume that moving the MRT file to a different location, fised the problem - it didn't.

I had tried to run it from the desktop before. And it didn't work.

My assumption is that applying:

net user administrator active:yes

and then applying

net user administrator active:no

immediately

may in some way have fixed the problem.

Though, that's a very big assumption on my part.

entered in error

I am responding to the initial post in this thread, but this information is intended for all 3 primary participants, since as usual it appears there is confusion about the use and true value of the MSRT.

The following covers most of the potential questions about this tool, though I'll include a more specific section from the MSRT download details about the log file the MSRT creates each time it runs below.

Remove specific prevalent malware with Windows Malicious Software Removal Tool

Removal results and log file 

After the standalone version of MSRT scans the computer and removes threats, it displays a report that lists the threats. It also generates the following log file:

 %windir%\debug folder\mrt.log

Along with the fact that the mrt.log contains any threats detected, it also may display error messages which might provide more detail into whatever problem(s) may be causing the failures seen during a scan.

Note that the purpose for the MSRT is to operate as a second opinion scanner typically once monthly to detect any of the most prevalent malware families currently affecting Windows systems of any sort worldwide.  This doesn't include all malware, just the most commonly known in the wild, so it isn't truly useful for finding all of the malware infecting a system.  Microsoft uses this information to help identify malware that's commonly bypassing the installed security application(s) on Windows systems to aid in the protection of the Windows ecosystem as a whole.

Using an alternative scanner such as the Malwarebytes Anti-Malware on-demand is more generally effective for individual PC manual scan purposes, since along with covering a larger range of malware, it's known for detecting many of the PUA (potentially unwanted applications in Microsoft terminology, often called PUPs by others) that most commonly get past the Microsoft security products.

The issue of the MSRT displaying potentially infected files during the scan which are later determined to not be infected is well known and now affects nearly all of the Microsoft security products as these clients have been upgraded the last few months.  This is due to the fact that the clients all buffer their initial detections of individual file or registry items until roughly the 90% point of the scanning process, at which point the MAPS (Microsoft Active Protection Service) components of the anti-malware client "phone home" to verify these items aren't either false positive or negative detections.  If not determined to be known malware, the potential malware counter is simply reset, while any unidentified suspect items will be uploaded for further analysis as with any MS client.

As for the OP core problem with the inability to execute the MSRT manually, this can occur due to malware modifications to the registry, but also potentially due to registry corruption from other events, so it doesn't itself define the issue as malware.  It does, though, require investigation much of which you've already attempted.  The fact that simply moving the file to a different location (i.e. desktop) seems to fix the problem makes me believe the problem is some sort of file, folder or registry corruption in the areas normally used when MSRT is executed manually, though that's only a guess.

Finally, note that using the MSRT to perform a "Full scan" is an oxymoron, since by definition the definitions it includes are limited, so though every file and folder on the Windows drives will be scanned only these limited number of common families can ever be detected.  This is not only why the scan takes so long, but also why some of the items listed as potential malware during the scan might relate to PUPs or other typically less malicious items that the MSRT won't detect, but even other Microsoft security products with more complete and current sets of definitions might.

Rob

It may also be worth noting that one software may not be as good as another.

Whilst we may prefer different things, you can see by the attached image, that MSRT is reporting some infections and Windows Defender found no problems.

So, what should be used or not, I'm not too sure.

I prefer to use all that I can.

That's why I posted here, to see if we could find out why my system was stopping me from running the tool.

And now, all of a sudden, it's working!

By the way, MSRT has only ever found a problem when I've run a full scan.