I recently updated to the latest kernel available in Debian testing (2.6.32-5), and whenever I shutdown my computer I get a segmentation fault when halt is called and the shutdown process never finishes. I can reboot without issues, but shutdown fails every time. If I boot in recovery mode and call halt immediately after logging in it still segfaults. I have attached a photograph of the stack backtrace after it segfaults. I have also reported this with the Debian bugtracking system. (http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=566547) That has all the information about my system that was automatically gathered, as well as some discussion about the problem so far.
Created attachment 24692 [details] A photograph of the stack backtrace after the segfault.
This appears to be a duplicate of bug 15005 which is fixed in 2.6.32.7.