So, I did some searching about the ATI driver and tried removing the fglrx-updates and fglrx-amdcccle-updates packages. On reboot, everything was working normally again. I'm not sure why these packages were installed--I'm fairly sure I didn't request them explicitly, and I didn't see anything immediately obvious in dpkg.log to suggest what other package may have pulled them in as a dependency or what not. In any case, as I've fixed the problem for myself, I'm closing the ticket. Feel free to re-open if you think there may be a bug that inadvertently installs these two packages.
Thanks so much for pointing me in the right direction! ** Changed in: xorg (Ubuntu) Status: Incomplete => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1132629 Title: OpenGL no longer functioning To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xorg/+bug/1132629/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs