For the record I verified the iso against the sha256 hash, and used cmp to compare the DVD and the iso (returned nothing)3) If you're using the same medium (or the same .iso) to install now as you used a year ago, it's certainly possible that either your .iso or your medium is corrupt. Have you verified the checksum on both the downloaded .iso file and the medium you're using? (At the risk of belaboring a point, verifying one without verifying the other is a waste of effort.)
The iso I used was: Debian Live 8.7.1 amd64 xfce, which I downloaded and burned to disk on Wednesday last week, so it was not the one I had used before.