Tuesday, August 12, 2008

Windows XP Login Logout Loop

Problem: The PC (which runs Windows XP with SP2) starts normally. The Windows splash screen appears correctly and then the login prompt correctly loads. You can then enter your user name and password like normal, but as soon as you try to login you are IMMEDIATELY logged back out again. The desktop doesn’t even load. It moves immediately back to the login window where you can then enter your user name and password again. No matter how many times you try to login you always experience this immediate logout. Even if you try to login to the computer in safe mode you still experience the same problem. This problem is documented on Microsoft’s website here.

Solution: I’m sure this behavior can be caused by many different problems, but the most common cause is a virus. If you’re familiar with the Windows registry, this virus changes a few registry key values that makes it impossible to login to your computer. If you’re not familiar with the registry, don’t panic. I’ll post links to a few articles that very clearly explain how to fix this problem. Basically, the virus makes two very simple changes to your computer that render it useless. In order to fix the problem, you have to change these two things back to the way they were while your computer was working.

Easy Fix: The “easy” solution to this problem can be found here. In order to use this fix you have to have your Windows XP install CD. This is the CD that contains the files necessary to install the operating system on your computer. You probably have this disk stashed in a drawer somewhere. You should note that there’s a difference between the Windows XP install CD and the recovery CD that may have shipped with your computer. It’s actually possible that when you bought your computer that it didn’t actually come with a Windows XP install CD. Sometimes computer manufacturers will only ship you a recovery disk, which is altogether different. You need your Windows XP install CD so that you can run an application called the Recovery Console. The link above should provide documentation on how to use the Recovery Console. Unfortunately, this fix didn’t work for John’s computer, but it may work for yours.

Slightly Harder Fix: This fix is the one that ended up working to fix John’s computer. A detailed explanation of this fix can be found here. It requires you to have access to another Windows PC with a CD burner (even if it’s a friend’s computer). You have to download a program called BartPE, which is one of the greatest recovery tools that exists. For this particular problem, BartPE will enable you to quickly change the two settings that the virus messed up. You may need a Windows XP install CD for this method as well. But it may be possible for the program to find what it needs from your friend’s computer without having to have access to this disk.

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