Since updating Ubuntu from 13.10 to 14.04.
If log out from session, get black screen and the "low graphics mode" dialog, sometimes with cursor, sometimes without.
Happens only when logout, and the driver is switched (via Catalyst Control Center) to use the Intel graphics. When using AMD graphics, logout is normal, but get a "do you want to report an error" dialog.
14.04 with latest fglrx. Dual head Pavillion dv6-6051er.
Askubuntu link: fglrx - black screen / low graphics mode on logout - Ask Ubuntu