Tried both run and repo installs of 346. CUDA is the special GTX9x0 version.
Found, by switching to lightdm, that the problem was a broken gdm. The login display was always black but no errors were reported in the Xorg logs. Gdm became broken at or near the time I installed the 346 driver, but the problem persisted with my Radeon card.
nvidia-bug-report.log.gz (137 KB)