finish uninstalling old version Avast free in order to install latest version

[jf22]

Hi Everone,
First of all I admit my guilt and cowardice in not updating Avast for far too long. Mea culpa.
I have two windows 7 computers and today I bit the bullet and updated the one I am writing on to the latest version of Avast with no problems.
Now I would like to update the other one, which, unfortunately became infected due to my negligence, an even older version of Avast. When the malware got worse I uninstalled my old Avas via uninstall in Windows and as others mention, some files were left behind. Meanwhile I am using MSE which also did not find the malware.
What i would like to do is just remove the left-behind files one by one in a simple manner. So first of all is this a super bad idea? Because even if I install something to help uninstall I am afraid that I will get an infected version.
Second, is there an outside chance that by installing the latest Avast version the left-behind files will be taken care of? I doubt it, but the simpler the solution the better for me. As I said above, the good news is that I am confident that the latest version of Avast will work fine on my other Windows 7 computer once I am properly prepared to install it.
Thanks for any help!

[Pondus]

You can check your comp with a online scanner, no install just a small client to run

Trend Micro Housecall  https://www.trendmicro.com/en_us/forHome/products/housecall.html

F-secure  https://www.f-secure.com/en/home/free-tools/online-scanner

ESET  https://www.eset.com/int/home/online-scanner/


Uninstall avast  https://support.avast.com/en-us/article/Uninstall-Antivirus/

[DavidR]

Once you have done some of the on-line scans suggested, as these could potentially prevent the reinstallation of Avast.

Clean Reinstall -
1. - Download the avast! Uninstall Utility, avastclear.exe https://www.avast.com/uninstall-utility and save it to your HDD.
Make a note of the steps required or print the page.
2. - Download the latest Avast off-line installation file for your Avast Program (see https://forum.avast.com/index.php?topic=249164.0) and save to your HDD.

Follow the instructions in the link in 1.

[jf22]

Thank you Pondus and DavidR. I will do everything you say and let you know how it goes. It may take me a few days because I am so busy these days.
jf22

[DavidR]

You're welcome, good luck.

[jf22]

Update: Ran the first of the scans suggested by Pondus--Trend Micro Housecall. Quite thorough, did require an .exe download, accept cookies, allow computer to make changes, etc. Scan took 31 minutes, didn't find any threats. One question about Trend Micro--while the copyright for the site is 2021, the copyright for Housecall was to 2020. Probably makes no difference but thought I would mention it.
This is getting ahead of myself but what if I don't find a threat? So far nothing found by complete scans of MSE and Trend Micro. Meanwhile I will continue running the other 2 scans suggested by Pondus and will continue to provide updates.
In other news the up-to-date version of Avast on my other Windows 7 computer continues to function perfectly.
As I said before, there will be some delays due to how busy I am at present.
Thanks again for the excellent help and support provided here at the WEBforum.

[DavidR]

If all other malware checks come up clean, then a clean reinstall would be your next step when time permits.

[jf22]

update:ran F-secure--no malware. Ran ESET--found 1 unsafe exe, and deleted it. This had to do with either Recuva or something in matlib. ESET noted that they have the same address.
 
Now I am turning to avastclear.exe and  have a question. The instructions say to download to desktop. Usually when I download a program it puts a shortcut on the desktop but not the program itself. So I want to check if this is okay. I may have some further questions. We shall see.
Thank you.

[jf22]

I already have an additional question. Reading the link Pondus provided for instructions for uninstalling Avast, mention is made of using a different uninstaller for computers that do not have SSE2 support. I do not know if my Windows 7 computer has SSE2 support or not. I tried to read about it but it was somewhat confusing. The processor is an IntelCore i5 CPU M540 @ 2.53GHz 2.53GHz. The GHz is written twice the properties description of the computer. Perhaps this info will help in determining the SSE2 support status and which uninstaller I should use.
Thank you,

[DavidR]

The program may well put a shortcut on the desktop after you install it, Avast are saying download it to the desktop, I have no idea why they are saying that.

I think this is more for ease to find later.  For me to choose your desktop for the download may be hard for you to actually point to that location, than your usual download location.

Personally for any download I just download it to a location of my choice, that way you can easily find again. Which is why I mentioned to download to your HDD (or SDD if that is your primary drive).

I have a specific download folder and not the windows user download folder and use that for all downloads.  I believe it should still work from that location.

####
SSE2 requirements are normally associated to old systems, that had old CPUs on the system even my very old XP SP3 with a core 2 duo supported SSE2.
Your Core i5 CPU will probably will almost certainly support, my core i5 CPU does see attached image.

[AZBruno]

Have you considered making a rescue disk from the latest Avast that installed fine and then trying to boot it onto the bad PC to run a scan.

[bob3160]

Have you considered making a rescue disk from the latest Avast that installed fine and then trying to boot it onto the bad PC to run a scan.

And how would you go about accomplishing this?

[AZBruno]

Have you considered making a rescue disk from the latest Avast that installed fine and then trying to boot it onto the bad PC to run a scan.

And how would you go about accomplishing this?

Go to the Protection > Virus Scans page and there will be a small "Rescue Disk" link on the right.

[DavidR]

Have you considered making a rescue disk from the latest Avast that installed fine and then trying to boot it onto the bad PC to run a scan.

And how would you go about accomplishing this?

Go to the Protection > Virus Scans page and there will be a small "Rescue Disk" link on the right.

The OPs has installed avast on one system but not the other yet, I don't know if creating a Rescue Disk would work across the board for different systems. But if close enough (same OS, etc.) it could well work.

https://support.avast.com/en-in/article/Use-Antivirus-Rescue-Disk/