Many thanks. I ran the MS DOS instructions as you suggested and first it found that the disk was NTFS, then finally the message came 'Windows found not problems'. After re-booting, the CHECKDISK on I message did not appear. Hopefully all is now well.
As to ESET, I un-installed and re-installed and the icon now appears. We will see if it continues. In the meantime many thanks for your help.