For the benefit of others who spent ages tracking this down: next time something weird happens to your video display, dive straight into /var/log/Xorg.0.log and do your best to make sense of it.
The penny dropped for me when I saw no error (EE) lines at all - as far as X was concerned, everything was working just fine (which would explain why the login screen's drum sound happened as expected, and why I was still able to switch consoles with Ctrl-Alt-F1 or cause an X restart with Ctrl-Alt-Backspace). But there was a line saying "Assigned Display Device: CRT-0" in there, and it occurred to me that not only was my flat panel completely black, but the backlight was turned off, as if X had been told to use an entirely different display. Googling "xorg options nvidia" got me here: http://http.download.nvidia.com/XFree86/Linux-x86/1.0-8774/README/appendix-d.html and a quick edit to the URL to match the nvidia driver version from Xorg.0.log got me here: http://http.download.nvidia.com/XFree86/Linux-x86/1.0-9631/README/appendix-d.html and the rest was straightforward. I still don't understand why, left to its own devices, the nvidia driver autodetects a CRT when there isn't one connected but doesn't detect my TV-out port at all; is this a Dell BIOS thing? It's good to have options available to override all the automatic behaviour, though. -- [nvidia-glx] X is blank after upgrade https://bugs.launchpad.net/bugs/82312 You received this bug notification because you are a member of Ubuntu Bugs, which is the bug contact for Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs