I have run Local Disk C Properties/Tools/Error checking/scan for and attemp recovery of bad sectors.
At the end of phase 2 it tells me that "Windows was unable to complete the disk check".
What might be the reason please?

Prior to above I have also run "Automaticaly fix file system errors". It has completed this section fully but found some errors and things. I was planning to post what was found but I am not able to find the log for this.
Thank you.