Comment 28 for bug 921384

I have try again. Same result. I have purge first all the fglrx packages and then sudo apt-get update && sudo apt-get dist-upgrade && sudo apt-get install fglrx.
At reboot lightdm doesn't start. I look at /var/log/apt/term.log and I can see that are present some error. Full log: http://pastebin.ubuntu.com/879984/

An abstract:
"update-alternatives: attenzione: saltata la creazione di /etc/OpenCL/vendors/amdocl32.icd poiché il file /usr/lib/fglrx/etc/OpenCL/vendors/amdocl32.icd associato (del gruppo x86_64-linux-gnu_gl_conf) non esiste.
update-alternatives: attenzione: viene forzata l'installazione dell'alternativa /usr/lib/fglrx/ld.so.conf poiché il gruppo x86_64-linux-gnu_gl_conf è danneggiato."

"update-alternatives: skip creation of /etc/OpenCL/vendors/amdocl32.icd cause /usr/lib/fglrx/etc/OpenCL/vendors/amdocl32.icd doesn't exist
update-alternatives: force installation alternative /usr/lib/fglrx/ld.so.conf cause x86_64-linux-gnu_gl_conf group is damage"