Kernel panic when changing channel

Following is the output when using iwconfig to change
the channel with version 0.2.0pre4 with either
dwl-650+ or dwl-520+. It works fine with 0.2.0pre3. I'm
running Mandrake 9.1 (2.4.21-0.25mdk)

# iwconfig wlan0 channel 6
# Unable to handle kernel NULL pointer dereference
at virtual address 00000000
*pde = 00000000
Oops: 0000
acx100_pci audigy ac97_codec sound soundcore nfsd
af_packet sr_mod floppy 8139too mii ntfs nls_utf8
nls_cp437 vfat fat supermount ide-cd cdrom ide-scsi
scsi_mod mod_quickcam videodev keybdev
mousedev hid usbkdb input ehci-hcd usb-uhci
usbcore rtc ext3 jdb
CPU: 0
EIP: 0010:[<00000000>] Not tainted
EFLAGS: 00010282
eax: c03ada4c ebx: dba3600c ecx: 00000000
edx: c03742a8
esi: 00000000 edi: fffffffe ebp: c037bf3c esp:
c037bf1c
ds: 0018 es:0018 ss: 0018
Process swapper (pid: 0, stackpage=c037b000)
Stack: c0124e50 00000000 c012459d c037bf28
c037bf28 00000000 c03a1560 fffffffe
c037bf44 c0121102 c037bf54 c0121014 00000000
00000001 c037bf70 c0120e4a
c03a1560 00000046 c039f900 00000000 c037bf90
c037bf88 c010a486 c03386fc
Call Trace:
[<c0124e50>] run_timer_list+0xf0/0x160 [kernel]
[<c012459d>] update_wall_time+0xd/0x40 [kernel]
[<c0121102>] bh_action+0x22/0x50 [kernel]
[<c0121014>] tasklet_hi_action+0x44/0x70 [kernel]
[<c0120e4a>] do_softirq+0xaa/0xb0 [kernel]
[<c010a486>] do_IRQ+0xb6/0xc0 [kernel]
[<c0107170>] default_idle+0x0/0x40 [kernel]
[<c010c918>] call_do_IRQ+0x5/0xd [kernel]
[<c0107170>] default_idle+0x0/0x40 [kernel]
[<c0107197>] default_idle+0x27/0x40 [kernel]
[<c0107212>] cpu_idle+0x42/0x60 [kernel]
[<c0105000>] stext+0x0/0x30 [kernel]

Code: Bad EIP value.
<0>Kernel panic: Aiee, killing interrupt handler!
In interrupt handler - not syncing