When you schedule a chkdsk <Drive> /f \[/r\], Chkdsk writes an Application Event Log entry similar to:
Event Type: Information Event Source: Winlogon Event ID: 1001 Computer: Computer_Name Description: Checking file system on C: The type of the file system is NTFS. Volume label is System. A disk check has been scheduled. Windows will now check the disk. Cleaning up minor inconsistencies on the drive. Cleaning up 153 unused index entries from index $SII of file 0x9. Cleaning up 153 unused index entries from index $SDH of file 0x9. Cleaning up 153 unused security descriptors. Windows has made corrections to the file system.NOTE: See tip 2217 » Windows 2000 chkdsk reports cleaning unused security descriptors?.