I downloaded Ubuntu Desktop from here and when I mounted the .ISO file I have folders and files like bellow:
then I compare to Ubuntu 15.04 ISO file which was mounted:
I tried to re-download Ubuntu 15.10 ISO twice to make sure there's no corrupted while downloading process, but it's the same.
Then I tried to use Ubuntu 15.10 without installing. After boot into live Ubuntu, I cannot perform anything. Then I discovered that all the apps were not installed. It's all empty even terminal.
What's wrong with that ISO file?