I'm having some huge problems installing ubuntu 15.10. Here's the story:
1) I used to have 14.04 on my PC and everything was working very happily. However, yesterday, I got a window proposing me to update to 15.04; during the usual update procedure I got plenty of error messages saying many packages couldn't be properly configured. At the end the installer said the update failed and tried to reset to old configuration. But something must have gone wrong, since I couldn't restart the pc. Thus, I decided to erase and install directly the latest version.
2) To backup I used an old 13.04 live CD and everything worked.
3) Meanwhile I created a 15.10 live USB. When I tried it, it couldn't create a live desktop, freezing on a black screen after the ubuntu logo. Also selecting "install" brought to a freeze immediately after the install window appeared.
4) I read for some hardware one needs to set "nomodeset" in grub and I did it. This indeed allowed me to begin the installation procedure; however, it freezed trying to connect to WiFi.
5) I connected to WiFi using the live 15.10 and launched the install afterwards. Everything worked.
6) However, when rebooting I get again a black screen after the ubuntu logo. Setting nomodeset in grub seems to be of no help now. I also tried to add nomodeset in /etc/default/grub in recovery mode, but the file opens in read-only mode with nano, so I cannot edit it
Do you have any suggestions?