Keyboard/Mouse non-responsive after screen-saver wake

[qwazi]

Dell Latitude E6400 w/ Intel video card
Ubuntu 11.10 64-bit

Ubuntu set to lock screen after 10 minutes. Sometimes (less than 50% of the time, but far too often for me) when trying to unlock the screen, no password dialog appears, but I can still move the mouse around and see windows that were open prior to the screen blanking. Keyboard appears to be unresponsive, but I can ctrl+alt+f1 to get to the command line.

From the command line, executing "sudo restart lightdm" gets me back to the login screen, but then after logging in my desktop is violently flickering. This is solved by a reboot.

This has been previously reported by others at askubuntu:
http://askubuntu.com/questions/84164/system-freeze-on-exit-from-screensaver-unity
http://askubuntu.com/questions/72692/system-freeze-on-exit-from-screensaver-unity-2d-older-intel-gpu

I'm currently seeing if uninstalling gnome-screensaver fixes the problem (although now, my laptop doesn't require a password to use).