Bug#456541: Unplugging causes laptop to suspend

[Neil Van Dyke]

I reported the same problem with a ThinkPad T42 (not T42p) at 
approximately the same time:

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=457533

Since then (and after doing Debian updates), sometimes I get a desktop 
notification of the AC->battery transition rather than a suspend.  
Usually I get a suspend.

Also since then, I've been seeing a perhaps related problem that the 
screen won't unblank, or will unblank briefly (1 second or less) before 
blanking again.  This occurs when I have left the laptop unattended for 
several hours, and greets me every morning.  I have to spend 5+ minutes 
experimenting with the lid latch, AC cable, etc. to try to get it to 
unblank.  The most disturbing part is that the screen will still be off 
even after a forced power off and temporarily removing the AC and 
battery to give a clean cold boot.  Could gnome-power-manager or 
underlying userspace or kernel code be corrupting some value that 
persists in the laptop's NVRAM?  (The other option I see is that I have 
a hardware failure (e.g., loose display cable) that just happened to 
occur at the same time as the other power management problems, or that 
was somehow triggered by that problem.)