I always tried to install proprietary drivers on ubuntu but i always failed. Last time i did it was yesterday.
I'm using Kubuntu 14.04.2 and a Juniper HD 5450 and i downloaded those drivers: Desktop ,i decided to not use repo's ones as i got really bad experience on ubuntu 14.10 using them,as bad as i got to format.
I choose the second option,"install on xorg ..." and all goes well. I reboot and even if splash screen is in low-res (but this is a known bug) system starts. I rebooted 2-3 times in the same day and all goes well.
This morning i start the pc and kubuntu does a disk control on boot. As always it reboots automatically and when splash screens comes again it is not a logo,but a text "Kubuntu 14.04". It happened me the same day when i had to shutdown the pc by case's restart button. But this time screen goes black for 2-3 minutes,i try to open tty and it doesn't work.
I reboot 2-3 times and the splash screen was the blinking logo of kubuntu. After some seconds,the logo just stops blinking and "locks",tty is not opening and i can't do anything more than rebooting.
I made the system start going to safe mode,remounting the hard disk to read-write and uninstalling drivers with amd-uninstall.sh
I had really similar problems with Ubuntu 14.10,downloading drivers from site and installing them.Is that something related to my video card?