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MB Scan running very slow

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I run a Malwarebytes scan every day. Normally, the scan takes about 25 minutes. Today, the scan took almost an hour and 9 minutes. It found no malware, but I was troubled by the great discrepancy between the scan's usual amount of time and today's time. After the scan had finished, I checked to see whether there was an update of any sort. I was told MB was up-to-date.   I downloaded and ran the MB Support Tool and have attached the results with this message.  I'm hoping you can tell me whether there's a problem.  Thanks in advance.


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I noticed some errors in your logs which may be signs of issues with the drive:

Windows Defender:
Date: 2021-05-04 18:59:21
Microsoft Defender Antivirus scan has been stopped before completion.
Scan Type: Antimalware
Scan Parameters: Quick Scan

Date: 2021-04-30 19:10:33
Microsoft Defender Antivirus scan has been stopped before completion.
Scan Type: Antimalware
Scan Parameters: Quick Scan

Date: 2021-04-26 18:59:59
Microsoft Defender Antivirus scan has been stopped before completion.
Scan Type: Antimalware
Scan Parameters: Quick Scan

Date: 2021-04-19 19:18:06
Microsoft Defender Antivirus scan has been stopped before completion.
Scan Type: Antimalware
Scan Parameters: Quick Scan
Error: (05/10/2021 12:10:50 PM) (Source: Microsoft-Windows-Defrag) (EventID: 264) (User: )
Description: The storage optimizer couldn't complete retrim on OS (C:) because: The operation requested is not supported by the hardware backing the volume. (0x8900002A)

Error: (05/10/2021 11:48:32 AM) (Source: Microsoft-Windows-Defrag) (EventID: 264) (User: )
Description: The storage optimizer couldn't complete retrim on RECOVERY because: The operation requested is not supported by the hardware backing the volume. (0x8900002A)

Error: (05/12/2021 10:07:58 AM) (Source: Service Control Manager) (EventID: 7000) (User: )
Description: The DefragFS service failed to start due to the following error: 
Indicates two revision levels are incompatible.

I also spotted one error about Malwarebytes itself having a problem:

Error: (05/10/2021 11:28:20 PM) (Source: Application Error) (EventID: 1000) (User: )
Description: Faulting application name: MBAMService.exe, version:, time stamp: 0x5fbd5689
Faulting module name: rtp.dll, version:, time stamp: 0x604be371
Exception code: 0xc0000409
Fault offset: 0x00000000001711cd
Faulting process id: 0xeb0
Faulting application start time: 0x01d745ad02322297
Faulting application path: C:\Program Files\Malwarebytes\Anti-Malware\MBAMService.exe
Report Id: 5f3eaadd-e7f0-461e-b483-5800eb232f07
Faulting package full name: 
Faulting package-relative application ID:

The first thing I would suggest would be backing up your data just in case there is any sort of issue with the drive, that way you don't risk losing anything.

Next, please see if a clean install of Malwarebytes helps at all:

  1. Run the Malwarebytes Support Tool
  2. Accept the EULA and click Advanced tab on the left (not Start Repair)
  3. Click the Clean button, and allow it to restart your system and then reinstall Malwarebytes, either by allowing the tool to do so when it offers to on restart, or by downloading and installing the latest version from here

While it is not impossible for a database update to impact scan times due to possible changes in how Malwarebytes' engine analyzes files to look for threats, I'd recommend playing it safe just in case something is going on with your hardware and backing up your data just to be safe.

Please let us know how it goes.


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Thanks VERY much, exile360, for your prompt and helpful response.  I have a question about what/how to back up. Once a month, I make an image using Macrium Reflect. However, that backs up more than data. Indeed, I don't know whether it backs up all my data. I've never had to resort to using an image backup. I'm also concerned that if there are problems, they might be saved when I back up whatever I'm backing up, and then reinstalled.  When you say "back up your data," what specifically are you referring to?  And what would be the best and simplest way to do that?  I'm embarrassed to be asking such elementary questions, but....

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I have one more question about what you reported, exile360. Apparently the Windows Defender scan has several times been interrupted. On the other hand, Windows10 keeps showing me that there are no security problems. It does report from time to time that it has started Windows Defender Antivirus because my version of Microsoft Security Essentials is incompatible with my version of Windows. I have not been able to find any remnants of Microsoft Security Essentials on my computer (which did use that before I upgraded the computer to Windows 10. Every time I start my computer, WinPatrol tells me that a program that used to be in the startup menu is no longer there: C:\Program Files (x86)\Windows Defender\MSASCUIL.EXE.  I can't find that program anywhere on my computer, but I also can't manage to stop WinPatrol from posting these daily messages. I have no idea whether any of this is relevant to what you reported about Windows Defender Antivirus being stopped several times, but I thought I'd mention it in case it is.

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Yes, if you're doing a full image backup with a tool like Macrium then you're fine.  It backs up everything, so you should be all set if worse comes to worse.

That said, if there are any documents, pictures, music or other personal files that you might need access to more urgently (such as anything related to work, if you use the system for that purpose), then I would recommend backing up those files to an external drive for safe keeping, that way you can access them on a different system later if needed, should this one fail.  Backing up such files is as simple as plugging in an external drive such as a USB flash drive or external hard drive and copying the files over.

Refer to this topic for a good list of resources and information on backing up your data.  Having an image backup of the system with Macrium is good, but it also means that the only way to recover your files would be to restore the system to that image, bringing all of the data and installed software and settings along with it, meaning you have no way to start fresh with a clean installation of Windows.

I don't believe remnants of MSE would cause Defender to stop a scan after starting it.  Since you did an upgrade from a previous version of Windows, if you can, performing a fresh install of 10 on the system might be a good idea just to refresh everything and eliminate any remnants from the previous Windows 7 OS, but of course that's up to you.

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Thanks very much, exile360, for your helpful reply. I am using a paid version of Macrium Reflect, and though I'm not sure, I think that it does support file level restoration. I might add that I save the images in an external hard drive that I connect to the computer only when I make the image. 

It may take me a while to decide how I want to proceed, but you've been extremely helpful. When I get everything sorted out, I'll let you know how/whether it worked. I might add that I'm a little surprised that the problem that made me write to the forum surfaced only today, given the dates of the problems noted in the report. As recently as yesterday's scan, there was no obvious sign of trouble.

Again, many thanks!

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Yes, if you've got the paid version, I believe it does indeed support file level recovery, so that's great.

It may be nothing, but as I mentioned, I'd rather play it safe just in case because I wouldn't want you to lose any important files if the issue does turn out to be hardware related.

In the meantime, please test to see if a clean install of Malwarebytes gets your scan times back to normal or not and let us know how it goes.  It may just be an issue due to a recent update causing parts of the scan to run more slowly.

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Thanks very much, exile360, for your continued help. I did a full image backup with Macrium yesterday. It took about the same amount of time as usual. This morning, I did my daily MB scan. I first checked to see whether there were any new updates and was told I was up-to-date. I then ran the scan, and it took 27 minutes, 27 seconds--well within what I usually experience. As usual, it found no malware. So I'm thinking that perhaps I don't need to uninstall MB and do a fresh install. If the problem recurs, I'll certainly try that, but for now, all seems back to normal (knock on wood, salt over my shoulder 🙂 ).

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Well, I think things are OK, but there was a complication after the MB Scan. It turns out the MB Window was blocking a small notice that said: "Unhandled Error: invalid pointer operation."  I asked DuckDuckGo for more info about Unhandled Error messages. Among the first was one that talked about how to deal with it on Windows 10. I was supposed to search for cmd, ask to have Administrative Control, then at the C:\WINDOWS\system32> prompt, type sfc\scannow. I did that, but soon there was a message that said "There is a system repair pending that requires reboot to complete. Restart Windows and run sfc again." So I restarted Windows. When that was completed, I decided that before I ran sfc again, I'd run another MB scan and see whether the Unhandled Error message appeard again. I ran the MB scan, which this time took 25m 46s. I then looked to see whether there was the Unhandled Error message. There wasn't!  My guess is that whatever Windows did fixed the problem, so I saw no reason to run sfc again. If I'm mistaken, or if there's someplace I should look to see what Windows actually did when I rebooted, please let me know.  My guess is that there was a Thunderbird or a Firefox update that I had approved a day ago but that perhaps didn't get installed. But that's just a wild guess.

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That is certainly a possibility, hopefully it was just an error on the file system that SFC repaired and not a sign of degradation of the drive.

I would suggest keeping an eye on it for any further issues, but as long as things continue to run normally (and you're keeping up to date backups of course), then you should be fine.

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