I have some problem about update Ubuntu. Once computer asked me to update version of Ubuntu from 12.10 to 13.04 (or 13... something like this). I click OK to update, but when the computer restarted again, it still was 12.10 (until now), and the speaker doesn't work, even I have tried everything with "setting". Sometimes the screen turns black automatically and I can't understand what's written and what to do. I have to force shut down because nothing happen after the black screen. What's happened? How can I do with this?