Sorry, I didn't read that post clearly either and thought it was you he was talking about..
I don't think they let you upgrade to 8.5 anymore, which is a shame. I think you are forced to go all the way to X2.
Look very carefully at the disk in a good light , it can be a microscopic piece of dirt. It can also be your DVD drive is acting up. Once again a dirty lens. There are lens cleaning disks, most of them not worth a pinch of c--n s--t. Try a can of computer air in there.