Yesterday, the system asked me if I wanted to upgrade to 13.10 from 13.04. Since that was the first time for me, I decided to proceed and ran the installation without worrying about it. After the system completed the upgrade, my PC was rebooted and the new version of Ubuntu signalled that the desktop would have run in low graphigs mode due to a graphical driver problem. I couldn't manage to fix the issue, so I continued with the low graphics mode... but nothing showed up. I wasn't even able to access one of the TTYs. So I ended up rebooting the system and accessing the recovery mode. I uninstalled all my ATI graphics drivers along with xorg-server and fglrx. After rebooting, I was able to access the login session of Ubuntu, but after confirming my credentials, the desktop wouldn't show up, but instead a black screen appeared with the following message: System program problem detected I couldn't figure out the problem and tried to restore/re-install all the graphics elements I knew. but nothing worked. The screen still remains black and won't show the icons nor the Unity bar. What would you advise me to do? Should I try launching a fresh install of the OS from the live CD? Thank you.