When you try to log on to a Windows XP computer, you receive as message like:

AuthUserInit Run-time error '53': File not found.

This behavior will occur if the Shell registry data is incorrect.

1. Press CTRL+ALT+DEL.

2. Press Task Manager.

3. Use the File menu and press New Task (Run...).

4. Type CMD.EXE /K and press OK.

5. In the CMD.EXE window, type the following commands, pressing Enter after each line:

REG ADD "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /V Shell /T REG_SZ /F /D "Explorer.exe"
REG ADD "HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" /V Userinit /T REG_SZ /F /D "%SystemRoot%\system32\userinit.exe,"

6. Shutdown and restart Windows XP.