Common Log (CLFS) Service Defaults in Windows 7

General-purpose logging service.

Default Settings

Startup type:Boot
Display name:Common Log (CLFS)
Service name:CLFS
Service type:kernel
Error control:critical
Group:Filter
Path:%SystemRoot%\System32\CLFS.sys
Registry key:HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\CLFS

Default Behavior

Common Log (CLFS) is a kernel device driver. In Windows 7 it is being loaded by Boot Loader before Kernel initialization. If Common Log (CLFS) fails to load, Windows 7 attempts to write the error data into Event Log and restart the computer, using the Last Known Good configuration. If the Last Known Good configuration is not valid, Windows 7 startup ends with a Stop error. If you remove or disable the CLFS service, Windows 7 won't start.

Restore Default Startup Configuration for Common Log (CLFS)

1. Run the Command Prompt as an administrator.

2. Copy the commands below, paste them into the command window and press ENTER:

sc config CLFS start= boot
sc start CLFS

3. Close the command window and restart the computer.

The CLFS service is using the CLFS.sys file that is located in the %WinDir%\System32 folder. If the file is changed, damaged or deleted, you can restore its original version from Windows 7 installation media.