Just followed the test again and this time I also tried booting using recovery mode.
Ubuntu booted up just fine. When an option to continue with failsafe X was offered I took it and then chose to run Ubuntu in low graphic mode.
Then I run gksudo jockey-gtk and jockey said that the nvidia driver is running properly and is activated, while it should say that something is wrong and ask whether to reinstall the driver.
Just followed the test again and this time I also tried booting using recovery mode.
Ubuntu booted up just fine. When an option to continue with failsafe X was offered I took it and then chose to run Ubuntu in low graphic mode.
Then I run gksudo jockey-gtk and jockey said that the nvidia driver is running properly and is activated, while it should say that something is wrong and ask whether to reinstall the driver.