Você deve verificar a corrupção do seu arquivo iso.
Uma maneira fácil de fazer isso é comparsão de hashsums.
Encontrei este na página inicial do Linux Mint:
Steps to verify an ISO image
The following steps should be performed to verify an ISO image:
Import the signing key from a Keyserver (see above). Verify its fingerprint with the following command:
gpg --list-keys --with-fingerprint
Download the ISO image, the sha256sum.txt and the sha256sum.txt.gpg into the same directory. Verify the signature on the sha256sum files with the following command (the output of this command should mention that the signature is "Good"):
gpg --verify sha256sum.txt.gpg sha256sum.txt
Once this is done, the sha256sum.txt can be trusted. Generate the sha256 sum of your ISO image, and compare it to the sum present in the sha256sums.txt file.
sha256sum -b yourisoimagefile.iso
If the signature was "Good" and the sha256 sums match, you successfully verified the integrity and authenticity of the ISO image.