ACPI and disappearing battery

[albright]

Hi everybody. I'm using mm-sources 2.6.1mm5 and noticed
something weird. After a while (minutes) after booting the battery
info in /proc/acpi/battery/BAT0 disappears. ACPI stops reporting
the state of the battery and I get of a lot of errors from
any battery monitor program, like this (in /var/log/messages):

Jan 21 20:18:18 haldir ACPI-1120: *** Error: Method execution failed [\_SB_.BAT0._BST] (Node c12d8a00), AE_ALREADY_EXISTS

I did *not* have this problem with the pre-release 2.6 kernels.
Anyway, help would be appreciated.