On rare occasion, opening the lid on my X40 to resume from hibernation results in a blank, but back-lit screen. I had the same problem more frequently when I was running Slackware 13. I can still SSH into the X40 and shut it down from there. I run XFCE.
I tried killing xscreensaver, xfce4-session, xfce4-power-manager, but nothing happened.
After rebooting, the Automatic Bug Reporting Tool throws a kernel warning:
[111848.029232] WARNING: at drivers/gpu/drm/i915/intel_display.c:915 assert_panel_unlocked+0xd1/0xe0 [i915]()