just in case -->( start computer go to grub !
Check your current kernel, type "e" than go to second line and write "single" at the end of this line.
than save your settings and boot from it (read instruction on a bottom of the screen).
This way you will get shell with root account !!!)
cd /usr/share/ati
su -c "sh ./fglrx-uninstall.sh"
and you fine again!