I've just tested this again, and the bug is still present as of the latest package incorporating 2.6.38.4: Linux jpc2 2.6.38-2-amd64 #1 SMP Sat Apr 23 18:47:49 UTC 2011 x86_64 GNU/Linux After completing the normal shutdown (unmounting file systems, etc.), the machine appears to stop very briefly and then it reboots.