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RESOLUTION to Fix Log on and Log off immediately issue

Method 1:

Navigate to the following registry key and changes the value of Shell and Userinit as mentioned below.

HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon

Shell = explorer.exe
Userinit=X:\windows\system32\userinit.exe

NOTE: These files may also be deleted by spywares. You may need to extract them using Windows CD or from another computer.

Steps for rectifying this Log on and Log off immediately problem:

Log on to a networked computer or any other computer in your home connected to the same network.
Open Registry and Point your cursor to HKEY_LOCAL_MACHINE.
Select File > Connect Remote Registry.

Type computer name (infected computer)
Navigate to the following location in registry of destination or infected computer.
HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon


Edit these two values in the right pane as mentioned.
Shell=explorer.exe
Userinit = x:\windows\system32\userinit.exe

6. Exit from Registry
7. Restart Infected computer.
8. You should be able to log on to computer and it won't do log off immediately.

If you don't have any other computer try the following step.

Try to boot the computer in safe mode with command prompt by pressing F8 during startup and selecting safe mode with command prompt.If it can be boot to safe mode with command prompt.

Open Registry Editor and Change the value of the following two entries in Registry key.
HKLM\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
Shell=explorer.exe
Userinit = x:\windows\system32\userinit.exe

If there is a key named "OldUserinit", delete the "Userinit" key and rename the "OldUserinit" key to "Userinit".

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