Logonui.exe Error Message

My sister turned on the computer this morning and the logonui.exe error message came up. We restarted the computer numerous times over half a hour, and it did not go away. This message said that the memory "cannot be read". I'm sending this from safe mode, where I checked on a previous solution someone offered about regedit.exe - windowsnt/software/windowslogon (I'm sorry, I cannot remember the exact path). I checked it and the data value is logonui.exe. We've been having the problem on and off for a couple of days, but not to the extent where we have to access files from safe mode. I would really like to go back to normal. Any help will be appreciated. I have all the XP CDs, AVG is up to date. I have read all the stuff on the Internet and none of it makes sense to me or applies to my problem. I ran AVG yesterday and the computer came up clean. I would really like some help - I just want the computer to go back to normal, so I can do my work.
Thanks

 

The file logonui.exe is a Windows core system file.
It should be in the Windows\system32 folder and should be between 504320 bytes (57% of all occurrences) and 514560 bytes.
There are some malware occurences of files disquised as loginui.exe. In these cases they are usually in the Windows folder (as opposed to the Windows\system32 folder) or in your C:\Program Files

While you are in Safe Mode you should check and see if this file is where it should be and if it is the correct size.
Let us know what you find.

 

I found the file and it is the right size.

 

OK
Now run the program sfc /scannow
(Start>Run then type "sfc /scannow" without the quotation marks. Make certain there is a space between the 2 parts of the command)
Either it will ask you to insert your XP CD or it will run the program automatically. It will check and replace any system files like logonui.exe, that it finds damaged or corrupted.
Reboot and then let us know if this fixed it.

One more thing.
Once you have run the sfc (which stands for System File Checker) you will have to reinstall all your hotfix files.
Go to microsoft.com and install all security updates.

 

It fixed itself last time, I'm not sure how. Yesterday - I turned it on again at 06:45 to run a scan (I find it easier to run early in the morning). The message came up. I went into Safe Mode for a minute, thinking it would help. I restarted the computer from Safe Mode and the message kept coming back. I have tried twice to go in Safe Mode and it hangs at the point where the list ends and just before the Safe Mode screen comes on - ie it says multidisk..... and then hangs. I restarted the computer and CHKDSK is currently checking for consistency. I'm letting that run in case, I don't know if it'll help. The only new software I added was the upgrade to RealPlayer yesterday. It required a reboot, which I did. The first time - the message appeared. The second time - it went back to normal. I'm fearing that I might not even be able to access Safe Mode. As soon as CHKDSK has finished, I'll update this thread. What I do not understand is

• what is logonui.exe
• what it means
• why it keeps coming
• how to fix it

Today - I turned the computer on again this morning and the message came back. I got it into Safe Mode and it works fine. I scanned the computer yesterday - it was clean. Someone sent me a file to download - http://www.dougknox.com/xp/scripts_desc/fix_xp_logon.htm. I can only run the program in Safe Mode and it said there were no errors. I cannot keep using Safe Mode. How do I fix it now? I do not know why it keeps happening. Yesterday, it took a hour for the Windows Desktop screen to come back. How do I stop the error message from coming back? I just really want it to go back to normal. I have to keep restarting it from the power button - I'm scared that I'm going to break it. I know there's no viruses on my computer. Are there any fixes I can run from Safe Mode, considering I cannot get anywhere else. I'm getting really annoyed now. CHKDSK ran again. It finished, repaired the errors, restarted and the error message came back. I have the computer in Safe Mode, what do I do now? Yesterday, CHKDSK ran, repaired the errors and went back to normal. What I can do is limited. I knew this would happen again.

Sorry if this seems long - I tried to put everything down.

 

You asked:

*logonui.exe is one of what are called the "core system files" in Windows. It is part of the process used by Windows to switch from one user account to another. Even if you have only one user account on your computer, this file is necessary for the stable running of Windows.

*Your error means that your copy of logonui.exe is probably corrupted and can not be loaded when Windows boots.

*The error keeps coming up because: the file itself is damaged and Windows needs the file.

*To repair this, the file must be replaced with a fresh copy.

The simplest way to do this is to run a small program called System File Checker. This program will examine all your system files by comparing them with a good copy of the file.
Some computers have copies of all their system files in a seperate part of the hard drive; some do not.
If your does, then this process is very simple; if your computer doesn't have this back up copy on the hard drive then you need a Windows installation disk to do the repair.

The way to run the System File Checker program is to click on your start button and then click on "RUN".
Type "sfc /scannow" (without the quotation marks) and then click "OK".
As I mentioned, the SFC program may ask you for the XP disk to be put into your CD drive.
Once this has been done you will have to reboot your computer, but hopefully it will be fixed.

 

I can only do it from Safe Mode and it will not let me run it. A box flashes and then nothing. I'll try again.

Same thing - box flashes and then nothing. I cannot go any further than Safe Mode. The computer won't let me. Is there anything I can do in Safe Mode to fix it?

 

I have a HJT log that I ran in Safe Mode. Would you like to see it? I do not know if it'll help. I really do not want to do a reformat of my hard drive and change everything because I cannot see a screen. I want it to be a really last resort.

 

Not sure if this'll help, but my winlogon file in c://windows/system32 is 502,272KB, size on disk - 503,808KB. It is file version 5.1.2600.2180.

 

Put your XP install disk in your CD drive and boot the computer.
When it asks you if you want to boot from the CD press your "ENTER" key on your keyboard.
The CD will now reinstall Windows XP.
When you get to where it asks if you want to install a new copy of Windows or repair your present copy type "R".
This will repair your XP but will not delete any of the other files on your computer.
Once this process has finished (it may take up to an hour), remove the XP CD and your computer should be back to normal.
You will however have to go to microsoft.com and update all the security patches that have been released since your copy of the XP CD was made.

 

I turned off the computer and turned it back on. It has just gone back to normal. How do I prevent it from happening again?

 

I wish I could tell you that.
Although it appears that you have repaired the problem, we never did figure out why it happened in the first place.
If it "rears its ugly head" in the future, let us know immediately and perhaps we can zero in on the cause.
Hopefully it won't.

 

It'll probably happen again in the morning. When it does come back, I'll post back here and let you know.
Thanks for the help so far.

 

It's back. I created a restore point yesterday after it went back to normal. I'm trying to restore it to that point to see if it works.

System restore did not work. I have a black screen now, instead of a blue screen. I'm going to try a repair of XP now, to see if that works.