each time i turn on my laptop i get a black screen with a window displaying message.c:\windows\system32\logonUI.exe then the ntvdm cpu has encountered an illegal instruction. i click on close and the screen goes black again i click on ignore and nothing happens. please help.
Did you try "safe mode"? You press F8 multiple times during the boot process. That should start the computer in safe mode.
This might be a virus issue that requires a reinstall of Windows.
The process Windows Logon UI belongs to the software Microsoft Windows Operating System or logonui.exe by Microsoft Corporation (www.microsoft.com).
Description: logonui.exe is located in the folder C:\Windows\System32. Known file sizes on Windows XP are 504,320 bytes (62% of all occurrence), 514,560 bytes.
File logonui.exe is a Windows core system file. The program is not visible. File logonui.exe is a Microsoft signed file. logonui.exe is able to record inputs, monitor applications, manipulate other programs. Therefore the technical security rating is 2% dangerous, however also read the users reviews.
Recommended: Identify logonui.exe related errors
If logonui.exe is located in the folder C:\Windows then the security rating is 72% dangerous. File size is 59,904 bytes. Program has no file description. The program is not visible. File logonui.exe is located in the Windows folder, but it is not a Windows core file. File logonui.exe is not a Windows core file.
If logonui.exe is located in a subfolder of "C:\Program Files" then the security rating is 64% dangerous. File size is 71,168 bytes. The application has no file description. The program is not visible. The application starts when Windows starts (see Registry key: HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run, HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run, HKEY_USERS\.DEFAULT\Software\Microsoft\Windows\CurrentVersion\Run). logonui.exe is not a Windows system file. logonui.exe is able to monitor applications.
Important: Some malware camouflage themselves as logonui.exe, particularly if they are located in c:\windows or c:\windows\system32 folder. Thus check the logonui.exe process on your pc whether it is a pest.
The possible culprit is that you picked up a virus or malware some where.
Since you can't do anything with it, suggestions would be try taking it in to a Reputable computer and have them repair it. which they would probably repair the installation of the OS. Or if you have the install disk for the laptop you could run the install for XP/Vista and repair it.
But I would make sure a get a good anti virus and malware removal program after you repair it.