iwi0: unknown hdr type

Running -CURRENT on an Thinkpad X32 with the standard onboard Intel
2915ABG wireless my system locks up hard if I switch to the console. I
get an endless flood of the following messages:

iwi0: unknown hdr type 47
iwi0: unknown hdr type 74

and between every six or seven of the those I see an
iwi0: unknown hdr type 8 or 9, its diffcult to read since it goes by so fast.

Perhaps related, occasionally the iwi0 interface will go down for no
apparent reason and when I try to bring it back up the system will
also lock up. I'm using the latest version of iwi-firmware in ports,
2.4_2.

Thanks in advance for any help.
William