How to Fix a Logonui.exe Application Errorby Mikhail Polenin
Your LogonUI process in Windows refers to the process that starts when you first log-in to your operating system. It shows you a screen where you select which users are allowed to enter the computer. Without this kind of process, you would not have the capability of creating multiple user accounts on the computer in the first place. To fix the process, you must expand the file from your operating system's CD onto your Windows system directory.
Put your Windows CD/DVD into your DVD drive.
Click your "Start" menu, click "All Programs," click "Accessories" and click "Run."
Type "expand D:\i386\logonui.ex_ %windir%\system32\logonui.exe" without the quote marks. Replace "D" with your CD/DVD drive. This replaces the corrupt LogonUI application with a fresh one from your operating system's installation resource.
Restart your computer and remove the disc from your drive.