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Fixed: Windows XP Logon Logoff Loop

One of my clients caught a virus on her computer this last week.  In an attempt to correct the problem, she installed Norton Antivirus 2010 before doing a full system scan using the boot disk.  The first time she rebooted the computer, she got into a logon logoff loop; after entering her login information and submitting it, Windows XP would automatically logoff the account.  It was at this point she contacted me and I came to help her solve the problem.  [See the bottom of this post for the solution]

I was stumped rather quickly after many internet searches.  I could tell the solution would not be easy.  The logon logoff loop persisted in all versions of safe mode; I was unable to access a command prompt.  I ran the bootable Norton CD and cleaned any remaining viruses off the machine; that didn’t solve the problem. My attempts to rename or copy files from another working machine, using a Windows Repair Console, did not solve the problem either.

Before telling my client I could not fix the problem, I called Norton to see if they could help me. Norton’s support was unacceptable, they could not help me.  I documented Norton’s inadequate support in a separate post.

I brought the computer to Best Buy, where my client originally purchased the Norton product.  I talked with the Geek Squad agent for a while, and we came to the same conclusion, a Windows Reinstall was most likely necessary.  I told my client I could do this at a fraction of the cost Best Buy would charge.

I attempted one last time to save the instillation of Windows, and returned to the internet once more.  I quickly realized I had managed to miss one of the possible solutions; fixing the registry.  I originally did not try this because I was unable to access Regedit.  This time, however, I brought some blank CDs and a copy of Windows XP Professional SP2 so that I could create a BartPE disk.  Using that disk I was able to open the local machine’s software registry hive and solve the problem.  My client’s computer booted successfully, and everything was as good as it was pre virus infection.

I learned two lessons with this service call:

  • Run a full system scan prior to an Antivirus instillation; the scan provided on the bootable CD.
    • The Bootable Norton CD will download new virus definitions automatically if the machine is connected to a LAN.
    • Installing Norton on an infected machine could possibly cause damage.
  • Come to all clients with all the tools at your disposal.  Even the tools you don’t think you will need.

Conditions

A Windows XP Professional machine was infected with several viruses.  Norton Antivirus 2010 was installed prior to a full system scan.

Symptoms

After rebooting, the system enters a logon logoff (or login logoff) loop; unable to get to the desktop. Safe mode will not work.

Solution

  1. Boot from BartPE disk (Download and creation instructions for BartPE)
  2. Open Regedit
  3. Select the HKEY_USERS hive
  4. Click File and choose Load Hive
  5. Open the SOFTWARE  registry hive, likely located in:
    C:\Windows\System32\Config\SOFTWARE (Note: No filename extension)
  6. Give the Hive a name: MyLocalHive
  7. Navigate to:
    HKEY_USERS\MyLocalHive\Microsoft\Windows NT\CurrentVersion\Winlogon
  8. Validate the value for the Userinit string equals:
    C:\Windows\System32\Userinit.exe, (Note: comma should be there)
  9. The preceding string and value may be missing and must be added
  10. Close Regedit and reboot the machine

Solution Credit: MVPS.org

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  1. Michael
    January 16, 2010 at 2:44 AM | #1

    My computer has been down for days and I just about exhausted all options to get it up and running because of this log on and log off loop. I was just about to give up when I stumbled across your post. After about 72 hours I finally got a real solution that worked. I tried every suggestion on every blog from easy fix to difficult and none worked. I was even using the BARTPE rebootable CD I created, followed someone elses instructions, but no such luck, it just wasn’t happening.

    Thanks again,
    Michael

    • January 16, 2010 at 8:23 AM | #2

      I’m glad it worked out Michael. I agree, way too many “fixes” that don’t work out there on the net!

  2. Bob
    January 28, 2010 at 8:58 PM | #3

    Thanks much much much,,, now maybe I can recover the rest of the operating system that got taken out, and I can back up my files now.

  3. Habib
    June 3, 2010 at 7:48 PM | #5

    I was messing with regedit before the logon logoff loop problem appeared at the next Startup. Your advice with the BartPE disk fixed my problem right away….thank you very much :)

  4. filoaman
    October 29, 2010 at 6:19 AM | #7

    I’d like to thank you. I spend many hours searching a solution for this problem.
    The only working solution was yours and now i have back my computer!!!!

    • October 29, 2010 at 8:11 PM | #8

      Glad everything is working now! Sorry it took so long though…

  1. January 8, 2010 at 8:13 PM | #1

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