My Thinkpad T61 (model 6465) behaves similarily: fails to reboot or shutdown while on battery.
I have found that removing e1000e module before reboot/shutdown solves the problem, so perhaps it is a bug in the kernel. The bug not occur on Squeeze + backports kernel, though. Cheers, Marcin -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org