Installed Avast. Did boot scan. Cant log on

 rivan -
I downloaded and installed the Avast AV (home) edition on my Windows XP (Service Pack 2) computer. After installation, it rebooted the computer and performed a boot level scan.

Some virus files were automatically moved to chest. Some were deleted. When it found the first file in the windows directory, I cancelled the scan.

The log on screen appeared but as soon as I logged on, the computer would immediately log me back off.

I tried safe mode with DOS prompt but I still can't log on.

Is there any way for me to uninstall the Avast AV product or fix the problem?


5 replies

Registration date
Tuesday September 30, 2008
Last seen
November 8, 2010
Hi npolar,

the reason why you're getting logged off immediately is because the userinit.exe on your system is either missing, deleted or was quarantined by your avast most probably, it must have been infected.

the resolution that you can do WITHOUT DATA LOSS is to get another copy of userinit.exe on the c:\windows\system32 directory usinf the windows recovery console which you will need to have you windows xp cd.

- or -

follow xpcman's advice.
Thank you

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I think that you are right. However, I was able to plug the laptop's hard drive into another computer using a usd to ide connector and copy off the information.

I then reformatted and reloaded the operating system.

The laptop is working again.

I learned a lot during this exercise.
Thank you so much guys

Registration date
Wednesday October 8, 2008
Last seen
June 15, 2019
You might be forced to re-install Windows. check this site for instructions on a Windows Repair/Install

Good Luck
I installed avast 4 (free) home edition on my laptop. After the installation, the computer will not let me logon. If I log on as administrator or any other user, the computer instantly logs me back off.
Safe mode, safe mode with command prompt, last good known setting etc do not work.

I copied back the original registry files from c:\windows\repair but this did not work.

I have been able to boot with the windows installation cd and go to the recovery console. From there, I deleted the avast files and disabled all the avast services except:
avast! antivirus
avast! web scanner and
avast! mail scanner

I think that if I can disable the above 3 services whilst in the recovery console, I can start up the computer.
To disable the other services, I used "disable <<service_name>>".
However, the above services are 2 and 3-part names and the regular disable command is not working on them. What commands should I use ?
I uninstalled the new version of Avast in safe mode, everything is fine now.
Registration date
Monday February 1, 2010
Last seen
September 1, 2021

Thank you for you feedback.

Im facing the same problem. downloaded Avast ystrday and ran a scan. There was a threat and avast suggested to do a boot scan. I clicked ok and scheduled for the boot scan to happen at the next restart. I restarted and it asks for a username and password. I dont have any user name or password on my system. What is this user name? I put in admin as username and password as password but it does not accept. I also put in the username (email id) and password given after registration of Avast but no good. I cannot get into safe mode by F8. Every restart asks for the username/password. Any ideas? Running Vista home premium.