I installed Kubuntu on my HP All in one Desktop Pavilion 23 four years ago. I have kept it updated, but would like to try another distro. I wanted to try Zorin, but for some reason I can only boot into Ubuntu. When I see the boot up menu, I can navigate to the DVD drive. However when I hit enter, nothing happens. I tried also with a USB and ran into the same problem. Does anyone have any idea what is causing this? Not sure if I should have asked here, or in the Ubuntu specific thread.