I have downloaded the ubuntu-14.04.3-desktop-amd64 Ubuntu version, I just did the md5sum check from the Windiws command prompt and had 414f5d28b2ac85d0e7aaf969f9bd0cb5
as a return.
As far as the md5 key given here is http://doc.ubuntu-fr.org/tutoriel/comment_verifier_l_integrite_de_son_image_cd#liste_des_empreintes_md5
is cab6dd5ee6d649ed1b24e807c877c0ae
does it mean I have to re-download it again?
Should I even delete the existing file?